Section — Koch–Preuss
Section 4: Sins Against Faith
Opposed to the virtue of faith are doubt, heresy, infidelity, schism, apostasy, and superstition.
- DOUBT.—Doubt is the state of a mind hesitating whether to give assent to a truth or to withhold it.1 As the formal object or motive of religious faith is the infallible authority of God, it would be irrational, and therefore sinful, to doubt anything that is contained in divine Revelation.
1 Cfr. John Rickaby, S.J., First Principles of Knowledge (Stonyhurst Series), p. 44.
“The faithful,” says the Catechism of the Council of Trent, “can have no doubt touching those things of which God, who is truth itself, is the author. Hence we understand how great is the difference between this faith which we have in God, and that which we yield to the writers of human history.”2
2 Cat. Rom., P. I, c. 1, qu. 1: “No doubt can occur to the faithful concerning those things of which God, who is truth itself, is the author. From this it is evident how great a difference there is between this faith which we have in God and that which we give to human histories.”
To doubt a doctrine which cannot stand the test of reason, either because it is not proposed by legitimate authority, or because all or some part of it is contradictory, is morally licit. Consequently, doubt is not forbidden per se, that is, not every kind of doubt is sinful, but there is a doubt that is reasonable and permissible.
A distinction must therefore be drawn between speculative doubt (also called theoretical or negative) and practical or positive doubt. The former has its origin in the intellect. When it is not directed against the substance of a revealed truth, but merely against the form in which that truth is couched, or against the arguments alleged in its support, or when it questions whether the dogma under consideration is really revealed by God or not, doubt is no sin, but rather a legitimate weapon against credulity, superstition, and intellectual sloth, and may prove an incitement to penetrate more deeply into the teaching of religion. When, on the other hand, a man harbors doubts against a truth of which he knows that, because proposed by the Church, it is surely contained in divine Revelation, he commits a sin, either of heresy or of infidelity.
Practical or positive doubt arises from the heart. It is the state of mind of him who, in the words of Jesus Christ, will not believe because he loves darkness rather than light.3 This kind of doubt is the product of a corrupt heart and logically leads to a denial of the faith and, in the end, to infidelity. “He that is of God, heareth the words of God; therefore you hear them not, because you are not of God.”4
3 John III, 19.
4 John VIII, 47; XVIII, 37; Rom. III, 4; IV, 19–22; 1 Thess. V, 21; Tit. II, 2.—Conc. Vatic., Sess. III, c. 3.—St. Anselm, De Fide Trin., c. 2: “For no Christian ought to dispute how that which the Catholic Church believes in her heart and confesses with her mouth is not so; but, always holding the same faith without doubt, loving it, and living according to it, he should humbly seek, as far as he can, a reason for how it is so. If he can understand, let him give thanks to God; if he cannot, let him not thrust in his horns for butting, but bow his head in veneration.” (Migne, P. L., CLVIII, 262).
There is a third species of doubt which is to be regarded as a temptation and is not sinful so long as the mind withholds assent. This form of quasi-doubt is sometimes a trial inflicted by God, sometimes the result of natural causes, physical or intellectual, and sometimes the product of carelessness, pride, self-conceit, or the sign of a secret repugnance to the truths of faith. It should be treated like scrupulousness, to which it is related.5
5 See this Handbook, Vol. I, pp. 199 sqq.—Cfr. F. Hense, Die Versuchungen, 3rd ed., pp. 237 sqq.; C. Krieg, Wissenschaft der Seelenleitung, Vol. I, Freiburg 1904, pp. 242 sqq.
- HERESY.—Heresy (αἵρεσις, from αἱρεῖσθαι, to choose) is error repugnant to the faith, pertinaciously held (error pertinax) by one who professes the Christian religion. It may be negative or positive. Negative heresy implies a denial of, or refusal to accept, a truth proposed by the Catholic Church; positive heresy asserts as a revealed truth something which the Church does not teach as such.
Heresy, again, may be internal or it may be external. It is internal (haeresis interna) if held purely as a matter of conviction; external (haeresis externa) if expressed in words or manifested by deeds.6
6 Cfr. Acts XXIV, 5; XXVI, 5; 1 Tim. I, 3; IV, 2; 2 John X; Gal. I, 6–9; Tit. I, 11.—St. Thomas, Summa Theol., 2a 2ae, qu. 11, art. 1.
Formal heresy involves rebellion against God and is a very grievous sin because it destroys the foundation of the means of salvation. “A man that is a heretic,” says the Apostle, “after the first and second admonition, avoid, knowing that he, that is such a one, is subverted and sinneth, being condemned by his own judgment.”7 “To have erred,” declares St. Augustine, “is human; pertinaciously to persevere in error is diabolical.”8
7 Tit. III, 10 sq.
8 Serm., 164 (al. 22, De Verbis Apost.), c. 10, n. 14: “To err was human; to remain in error through obstinacy is diabolical.” (Migne, P. L., XXXVIII, 901).—Cfr. A. Seitz, Die Heilsnotwendigkeit der Kirche, pp. 83 sqq.
Material heresy (haeresis materialis) is the error of those who do not pertinaciously reject the teaching of the Church, but err in good faith, i. e., sincerely desirous of knowing the truth. This kind of heresy is sinful only when the error is inexcusable. A non-Catholic who is in good faith and believes that he has the true religion, lives in a state of excusable error. If serious doubts arise in his mind concerning the truth of what he believes, he is bound to enquire, and if his enquiry results in the conviction that the Catholic Church is the true Church of Christ, he must give up his erroneous belief, else his heresy will cease to be material and become formal. For every honest man is obliged to renounce, both internally and externally, a religion which he recognizes as false and to accept that which his conscience tells him is true. He who knowingly persists in religious error incurs the condemnation of Christ, who says: “He that shall be ashamed of me and of my words, in this adulterous and sinful generation, the Son of man also will be ashamed of him, when He shall come in the glory of his Father with the holy angels.”9
9 Mark VIII, 38; cfr. John XII, 48.
A heresy is never formal, or grievously sinful, if it involves no real error against the faith (positivus assensus falsi seu dissensus veri), or if the holder is not a professed Christian, or the error is not deliberate and pertinacious.10 Involuntary error or error based upon ex- cusable ignorance is not even venially sinful. The distinctive mark of formal heresy, therefore, is wilful and obstinate rejection of a Catholic dogma. Hence the declaration of sincere Catholic writers: “I may err, but I shall never be a heretic.”11
10 Cfr. St. Augustine, De Civ. Dei, l. XVIII, c. 51, n. 1: “Heretics [are] those who under the Christian name resist Christian doctrine.” (Migne, P. L., XLI, 612).—IDEM, Epist., 43 (al. 162), c. 1, n. 1: “Those who defend their opinion, however false and perverse, with no obstinate animosity, especially an opinion which the audacity of their own presumption did not produce, but which they received from parents seduced and fallen into error, and who seek the truth with cautious solicitude, ready to be corrected when they have found it, are by no means to be numbered among heretics.” (P. L., XXXIII, 160).—IDEM, De Gestis Pelagii, c. 6, n. 18: “It matters how much, it matters whence, finally it matters whether, upon being admonished, he corrects it, or by obstinately defending it even makes into a dogma what he had said through levity, not as a dogma. Therefore, although every heretic is consequently also a fool, not every fool is immediately to be called a heretic.” (P. L., XLIV, 351).—IDEM, De Anima, l. III, c. 15, n. 23: “These things, if each is defended obstinately, can make as many heresies as there are opinions numbered.” (P. L., XLIV, 522).—IDEM, De Bapt. contra Donat., l. IV, c. 16, n. 23: “I do not yet call him a heretic, unless, after Catholic doctrine has been manifested to him, he chooses to resist the faith and chooses that which he held.” (P. L., XLIII, 169).—St. Thomas, Summa Theol., 2a 2ae, qu. 5, art. 3.—A. Seitz, Die Heilsnotwendigkeit der Kirche, pp. 59 sqq., 89 sqq.
11 Cfr. St. Celestine I, Epist., 25, n. 3: “Nor shall I give to this perfidy the name of error; not every impiety is error.” (Migne, P. L., L, 550).—Conc. Lateran. IV., c. 2 (Denzinger-Bannwart, n. 432).—Cicero, Phil., XII, 2: “It belongs to any man to err; to none but a fool to persevere in error.”—A. M. Weiss, O. P., Lutherpsychologie, 2nd ed., pp. 29 sq.
As against heretical errors, the teaching of the Church is called by St. Paul “sound doctrine” or “the sound word.”12 “Heretics,” says St. Ignatius of Antioch, “are scarcely to be cured; there is one physician, ... Jesus Christ our Lord.”13
12 1 Tim. I, 10; Tit. I, 9; II, 1, 8; cfr. 2 Tim. II, 17.
13 Epist. ad Ephes., c. 7 (Funk, Patres Apost., Vol. I, 2nd ed., p. 218, 17).
The chief sources of heresy are ignorance and pride.14 St. Augustine says that if there were no pride in the hearts of men, there would be neither heresy nor schism.15 It seems strange to have this truth confirmed by Martin Luther. “Every heretic and proud man,” he says in his commentary on the Epistle to the Romans, written while he was still a Catholic, “is first misled by ignorance of the divine truth. Then he accepts as true what seems to him to be true, and is already trapped, because he proceeds securely, as if he were true and free, beyond snares and imprisonment. In course of time he objects to everything that does not suit him and turns away his ears. Finally he gets angry and zealously defends the creatures of his brain, persecuting his opponents, slandering them, and inflicting all manner of injury upon them. The consequence is that he becomes utterly blind and cannot see what others see, and while all the rest rise up, he remains lying on the ground, defending his opinions.”16
14 Cfr. Matt. VII, 15 sq.; XV, 14; XXIII, 2 sqq.; Luke VI, 39; Acts XX, 29 sq.; Col. II, 8.
15 De Vera Religione, c. 25, n. 47: “If this [pride] did not exist, there would be neither heretics nor schismatics, nor those circumcised in the flesh, nor worshippers of creatures and images.” (Migne, P. L., XXXIV, 142).—IDEM, Enarr. in Ps., 124, n. 5: “Do not think, brethren, that heresies could arise through certain small souls. None but great men have made heresies; but the greater they were, so much the more evil were those men.” (P. L., XXXVII, 1652).—IDEM, ibid., 134, n. 18: “There are learned men who afflict the Church by making schisms and heresies.” (P. L., XXXVII, 1750).—IDEM, ibid., 106, n. 14: “They [the heretics] are leaders, they are learned, they are great, they are precious stones.” (P. L., XXXVII, 1429).—IDEM, Serm., 46 (al. 165, De Temp.), c. 8, n. 18: “In different places there are different sects, but one mother, pride, has begotten them all.” (P. L., XXXVIII, 280).
16 Commentary on St. Paul’s Epistle to the Romans, fol. 241b, apud Denifle, Luther und Luthertum, Vol. I, 2nd ed., p. 478.
- INFIDELITY.—By infidelity (ἀπείθεια, infidelitas) we mean an absolute lack of faith in the Christian religion.
a) If this lack of faith arises from invincible ignorance, it is called negative and is no sin, but merely an evil or a penalty of sin. If, on the other hand, infidelity arises from unwillingness to know or accept the truths of Revelation (infidelitas positiva), it is per se sinful. “If I had not come and spoken to them,” says our Divine Saviour, “they would not have sin; but now they have no excuse for their sin.”17
17 John XV, 22.—Cfr. Prop. Damnat. Baii, n. 68: “Purely negative infidelity in those to whom Christ has not been preached is a sin.” (Denzinger-Bannwart, n. 1068).—St. Thomas, Summa Theol., 2a 2ae, qu. 10, art. 1: “Infidelity can be taken in two ways: in one way according to pure negation, so that one is called an unbeliever from this alone, that he does not have faith; in another way infidelity can be understood according to contrariety to faith, whereby, namely, someone resists the hearing of the faith or even despises it; and in this the nature of infidelity is properly completed, and according to this infidelity is a sin. But if it is taken according to pure negation, as in those who have heard nothing of the faith, it does not have the nature of sin, but rather of punishment, because such ignorance of divine things followed from the sin of our first parent.”
Positive infidelity, as a rule, amounts to more than mere negation; it opposes to the true faith, which it rejects, some false doctrine of its own invention. Its sources are ignorance, pride, sensuality, and malice.18 The degree of sinfulness involved in each case is to be measured by the gravity of the underlying cause.
18 Cfr. Luke XVI, 27–31; John III, 19 sq.; V, 44–47; VIII, 42–47; X, 24–26; Eph. IV, 17–19; 1 Tim. I, 19 sq.—P. Segneri, Incredulus non Excusabilis, Dillingen 1696.—A. Guyot, Les Causes de l’Incredulité, 6th ed., Paris 1904.—A. Kirchberger, Der Unglaube und die Vernunft, Ravensburg 1907.—Pohle-Preuss, God: His Knowability, Essence, and Attributes, 4th ed., St. Louis 1921, pp. 52 sq.
The sinfulness of infidelity may be judged from what has been said above19 on the necessity of faith. The subjective guilt involved in each case varies according to the degree of consciousness and pertinacity with which the truth is rejected and is objectively graver if it disfigures the truths it denies.20
19 Supra, pp. 6 sqq.
20 St. Thomas, Summa Theol., 2a 2ae, qu. 10, art. 3: “Every sin formally consists in turning away from God. Hence a sin is the graver, the more a man is separated from God through it. But through infidelity man is especially removed from God, because he does not have a true knowledge of God; and through a false knowledge of Him he does not approach Him but is removed farther from Him. Nor can it be that one who has a false opinion of God knows Him in some respect, because that which he supposes is not God. Hence it is manifest that the sin of infidelity is greater than all sins which occur in the perversity of morals. It is otherwise with the sins opposed to the other theological virtues.”
Infidelity is really the most grievous of all sins because by it a man departs farther than by any other sin from God, who is man’s last end.21 The terrible consequences of unbelief are variously described in Holy Writ. “He that believeth not shall be condemned;”22—“He that believeth not the Son, shall not see life, but the wrath of God abideth on him;”23—“If you believe not that I am he, you shall die in your sin;”24—“The wrath of God cometh upon the children of unbelief,”25 etc.
21 St. Augustine, Tr. in Ioa., 89, n. 1: “He wishes a certain great sin to be understood, not every sin as though under a general name. For this is the sin by which all sins are held fast; if anyone does not have it, all sins are forgiven him.” (Migne, P. L., XXXV, 1856).
22 Mark XVI, 16.
23 John III, 36.
24 John VIII, 24; XII, 48; Rom. XI, 20.
b) There are various forms of infidelity.
α) Indifferentism (latitudinarianismus), or carelessness in religious matters, based upon the assumption that all religions, or at least all Christian denominations, are equally true or equally false (theoretical indifferentism),26 or sloth in the fulfilment of the duties imposed by religion (practical indifferentism).27
26 2 Cor. VI, 14–16.—Encyclical of Pius IX, Dec. 9, 1846: “To this pertains that horrible system of indifference concerning any religion, most repugnant even to the natural light of reason, by which those deceivers, having abolished every distinction between virtue and vice, truth and error, decency and disgrace, imagine that men can attain eternal salvation in the worship of any religion whatsoever, just as though there could ever be any fellowship of justice with iniquity, any society of light with darkness, or any agreement of Christ with Belial.” (Syllab. Error., n. 15–18; Denzinger-Bannwart, n. 1715 sqq.).
27 Apoc. III, 15 sq.
β) Eclecticism, so called, i. e., the arbitrary se- lection from the body of religious or philosophical truths presented by the Church of certain doctrines and combining them into a system; γ) Scepticism, which regards uncertainty or doubt as the product of reflection and the normal state of the human mind, and thereby completely renounces the knowledge of truth; δ) Formal or positive atheism in its various forms (Pantheism, Materialism, Naturalism, Rationalism), all of which agree in rejecting God and divine Revelation.28
28 Pii IX. Syllab. Error., n. 1–14 (Denzinger-Bannwart, n. 1701 sqq.).—J. Engert, Der naturalistische Monismus Häckels, Vienna 1907, pp. 208 sqq., 247 sqq.—W. Monod, Aux Croyants et aux Athées, 2nd ed., Paris 1910.—G. Grupp, Jenseitsreligion, Freiburg 1910, pp. 41, 95.
All these forms of unbelief are grievously sinful, though the personal guilt of individual unbelievers is often diminished by the influence of a wrong or defective training, by the power of deeply rooted prejudices or lack of proper instruction.
The reason why so many refuse to accept divine Revelation is not that they think too deeply, but that they do not think deeply enough. It is often asserted that a thorough training in the natural sciences (now-a-days called “Science” par excellence) destroys religious conviction. But this claim is untrue and can be easily refuted by the example of the many great scientists who have openly professed belief in God and the existence and knowability of miracles.29
29 K. A. Kneller, Das Christentum und die Vertreter der neueren Naturwissenschaft, 2nd ed., Frei- burg 1904 (tr. by T. M. Kettle, Christianity and the Leaders of Modern Science, St. Louis 1911). Father Kneller brings overwhelming evidence to show how the real leaders of scientific thought are forced to recognize, if not always the truth of revealed religion, at least that of the groundwork on which it rests. See also the three volumes of James J. Walsh’s excellent work, Catholic Churchmen in Science, Philadelphia, The Dolphin Press, 1913 sqq.—G. Sortais, La Providence et le Miracle, Paris 1905.—E. Dennert, Vom Sterbelager des Darwinismus, 6th ed., Stuttgart 1905 (English tr., At the Deathbed of Darwinism, by E. V. O’Hara and J. H. Peschges, Burlington, Iowa, 1904); C. Gutberlet, Vernunft und Wunder, Munich 1905.
To solve the problem offered to the human mind by miracles we must try to view them from the viewpoint of Almighty God rather than from our own limited coign of vantage. Miracles are not detached phenomena, but parts of a wonderful system of government. They are wrought by the same God who has conceived and created the universe. This is the true metaphysical harmony. “To the Lord was his own work known from the beginning of the world.”30
30 Acts XV, 18.
Why should the chemist, the physicist, the botanist, the zoölogist, the meteorologist, the astronomer, the anthropologist, the physician or the technician be hindered in his work by accurate notions of God, the world of spirits, the human soul, or the origin, purpose, and end of man? In every field of scientific research there have been and are eminent men who have not only preserved, but deepened and strengthened their religious faith. He who proclaims religion and science to be irreconcilable merely proves that he is ignorant of the true meaning of dogma, the real significance of religious ceremonies, and the authentic interpretation of the mysteries of faith. Unfortunately, those who have achieved eminence in some branch of science as a rule devote little or no time to the study of religion. A learned mind needs more than the elementary instruction imparted in the catechism. Religion, like science, has its technical literature, and its representatives are ready to explain and defend whatever the Church teaches. Those who attack the Christian religion usually have but a vague notion of its sources and methods, even though they constantly harp on the need of original research and critical acumen in their own chosen field. Now he who neglects or refuses to devote serious study to philosophy and theology, has no right to draw philosophical or theological conclusions from the data furnished by natural science. To do so is to mistake the essence of religion, which, though it may be practiced by all, even the most ignorant, can be scientifically demonstrated only by those properly equipped for the task. Theology, like every other science, must be studied from its own sources and by its own methods, though, of course, there are many points of contact between it and the natural sciences. Thus the law of causation, the teleological principle, the laws of nature, and other data furnished by natural science lead the mind almost imperceptibly and with a kind of elemental necessity from the contemplation of the results of empirical research to religious speculation and a study of the supernatural.
- SCHISM (σχίσμα) technically denotes a formal separation from the unity of the Church, and in this sense is not a direct antithesis of faith. But experience teaches that a state of pure schism, i. e., schism without heresy, cannot continue long, at least in the case of a large number of men. St. Jerome says: “Schism, at the beginning, may be understood as something different from heresy, but there is no schism which does not invent for itself some heresy, in order to justify its secession.”31
31 In Tit., c. 3, quoted by St. Thomas, Summa Theol., 2a 2ae, qu. 39, art. 1.
- APOSTASY (ἀποστασία) is of three kinds.
a) Apostasy from the faith (apostasia a fide)32 implies formal abandonment of the religion of Christ, coupled with the profession of some anti-Christian system (Judaism, Mohammedanism, paganism).
32 Thess. II, 3; 1 Tim. IV, 1 sq.—St. Thomas, Summa Theol., 2a 2ae, qu. 12.
b) Apostasy from ecclesiastical obedience (apostasia ab ordine) is committed by a Catholic who wilfully and contumaciously sets at nought the authority of the Church.
c) Apostasy from religious profession or from Holy Orders (apostasia a religione) is the sin of those who without permission abandon the religious order in which they are professed, or, after having received major orders, renounce the clerical profession and return to the dress and customs of the world.
Essentially, all three kinds of apostasy consist in abandoning or denying the truths of Revelation and embracing a religious system opposed to Christianity. Wilfully and contumaciously to abandon the Catholic faith is a sin against the Holy Ghost.33 A Catholic can never have a le- gitimate reason for leaving his Church.34 “There is no parity,” declare the Fathers of the Vatican Council, “between the condition of those who have adhered to the Catholic truth by the heavenly gift of faith, and of those who, led by human opinions, follow a false religion; for those who have received the faith under the teaching of the Church, can never have any just cause for changing or doubting that faith.”35 Sacred Scripture attributes apostasy from the faith to the Devil, who is the author of evil and the father of lies. False apostles, says St. Paul, “are deceitful workmen, transforming themselves into the apostles of Christ, and no wonder, for Satan himself transformeth himself into an angel of light.”36
33 Heb. VI, 4–6; X, 26–29; 2 Pet. II, 21. See this Handbook, Vol. II, pp. 91 sqq.
34 Prop. Damnat. sub Innocentio XI., n. 20: “Hence someone can prudently repudiate the supernatural assent which he had.” (Denzinger-Bannwart, n. 1170).
35 Conc. Vatican., Sess. III, c. 3: “The condition of those who have adhered to Catholic truth through the heavenly gift of faith is by no means equal to that of those who, led by human opinions, follow a false religion; for those who have received the faith under the teaching authority of the Church can never have any just cause for changing that faith or calling it into doubt.” (Denzinger-Bannwart, n. 1794).
36 2 Cor. XI, 13 sq.; cfr. Gal. V, 7 sq.
- CREDULITY (temeraria credulitas, in opposition to pius credulitatis affectus) means proneness to believe without sufficient evidence. In matters pertaining to faith and morals credulity is immoral because it runs counter to reason. The Catholic Church admonishes all men to scrutinize carefully whatever is offered in the name of religion without the warrant of divine authority.37 Credulity leads to superstition, “the twin-sister of unbelief,” or at best to an emotional pietism without true religious conviction and genuine faith.
37 Matt. VII, 15; Rom. XII, 1; 1 Thess. V, 21; 1 Pet. III, 15; 1 John IV, 1.—St. Augustine, De Utilitate Credendi, c. 11, n. 25: “Believing is then blameworthy when either something unworthy is believed about God, or something is easily believed about a man.” (Migne, P. L., XLII, 83).—St. Anselm, Cur Deus Homo, I, n. 2: “Just as right order demands that we believe the profound things of the Christian faith before we presume to discuss them by reason, so it seems negligence to me if, after we have been confirmed in faith, we do not strive to understand what we believe.” (P. L., CLVIII, 362).
It is charged that Christianity demands a sacrifice of the intellect (sacrificium intellectus). This is true in a sense, and could not be otherwise, as Christianity is a divinely revealed religion. However, the Church does not demand blind obedience, but merely “a reasonable service,”38 which enables the believer to say with the Apostle: “I know whom I have believed.”39 Ours is an enlightened faith, which fills us with joy and confidence and gives us the strength which we need to perform our duties. The ideal state of the soul is as far removed from credulity as from scepticism. He who believes too readily is as easily deceived as he who deliberately shuts his mind to the truth.
38 Rom. XII, 1; cfr. 2 Cor. X, 5.
39 2 Tim. I, 12.
Because of the importance of the true faith, the Church has taken special precautions to keep it pure. These precautions are embodied mainly in the organization against evil literature which is generally called the Index, and consists of three parts—preventive censorship, the prohibition of books, and the Index itself. The consideration of these measures belongs more particularly to Canon Law, and we will therefore confine ourselves to a few necessary remarks towards the end of this volume.40
40 Infra, pp. 399 sqq.
READINGS.—H. Noldin, S.J., Summa Theol. Mor., Vol. II, pp. 28 sqq.—Ern. Müller, Theol. Mor., Vol. II, 5th ed., Vienna 1887, pp. 37 sqq.—J. B. Ferreres, S.J., Compendium Theol. Mor., Vol. I, 9th ed., Barcelona 1918, pp. 186 sqq.—Thos. Slater, S.J., A Manual of Moral Theology, Vol. I, New York 1908, pp. 174 sqq.—A. Lehmkuhl, S.J., Theol. Mor., Vol. I, 11th ed., Freiburg 1910, pp. 236 sqq.
On doubt and skepticism in religious matters: J. L. Balmes, Cartas a un Eseptico, Barcelona 1851 (English tr., Letters to a Sceptic, Dublin 1875).—F. Hettinger, Apologie des Christentums, Vol. I, 9th ed. (edited by E. Müller), pp. 5 sqq.; in English under the title, Natural Religion, London 1890.—B. Kuhn, Formes Actuelles du Doute, Bruxelles 1906.—P. Jäger, Zur Überwindung des Zweifels, Tübingen 1906.—L. J. Walker, S.J., art. “Scepticism,” in the Catholic Encyclopedia, Vol. XIII, pp. 516 sqq. (See also the literature cited in Pohle-Preuss, God: His Knowability, Essence, and Attributes, 4th ed., St. Louis 1921, p. 54).—H. Noldin, S.J., Summa Theol. Mor., Vol. II, pp. 35 sqq.
On infidelity: P. Segneri, Incredulus non Excusabilis, Dillingen 1696.—A. Guyot, Les Causes de l’Incrédulité, 6th ed., Paris 1904.—Ch. H. Vosen, Das Christentum, 5th ed. (by S. Weber), Freiburg 1905, pp. 46 sqq.—A. Kirchberger, Der Unglaube und die Vernunft, Ravensburg 1907.—Ad. Tanquerey, Synopsis Theol. Mor., Vol. II, Paris 1905, pp. 378–390.
On schism: St. Thomas, Summa Theol., 2a 2ae, qu. 39.—J. Forget in the Catholic Encyclopedia, Vol. XIII, pp. 535–539.