Article — Vermeersch, Theologia Moralis
Article I: On Tempting God
What it is to tempt God. 1. The reverence owed to God requires that we have recourse to the special help of God and to His attributes modestly, discreetly, and humbly. To will that He should exhibit Himself as if on a stage is gravely injurious to God. Whoever, therefore, without cause, asks for the intervention of God commits this malice. Therefore the proper ratio of tempting God is in the rash demand for divine intervention. To this malice there can be added a sin against faith and hope, if someone, as if doubting, formally wishes to explore the divine truth or attribute, and thus thinks of tempting God more strictly, or of proving Him by experience.
Various concepts. Theologians do not all conceive tempting God in the same way. For some it is rash exploration of the divine perfection; for others, however, rash exploration of the divine good pleasure. They distinguish express temptation, which intends exploration, and interpretative temptation, which lies hidden in the manner of acting. Each is formal when, whether doubting or not, someone with conscious rashness asks that God come to his aid or manifest Himself.
Who are guilty of tempting God. He tempts God who, without a special divine instinct, absolutely wills or promises a miracle; or who, without sufficient cause, wills a miracle conditionally, if it please God, as if someone offers a miracle to prove the truth of faith; if someone, in a slight matter, or when other means are at hand, asks for a miraculous sign. The former will of itself be a mortal sin; the latter in practice will generally be excused from grave sin by some simplicity and slight insistence.
Common use. In common speech he is said to tempt God who rashly exposes his health, who preaches or teaches without preparation, insofar as he seems to demand an undue divine help. But this is rather presumption, which is opposed to another precept, for example the fifth. For where expectation of divine help is lacking, temptation of God is necessarily absent. - The gravity of the guilt must be judged from the importance of the foreseen harm.