That by Divine Law men are obliged to a Right Faith

AS sight by the bodily eye is the principle of the bodily passion of love, so the beginning of spiritual love must be the intellectual vision of some object of the same. But the vision of that spiritual object of understanding, which is God, cannot be had at present by us except through faith, because God exceeds our natural reason, especially if we consider Him in that regard under which our happiness consists in enjoying Him.

2. The divine law directs man to be entirely subject to God. But as man will is subjected to God by loving Him, so his understanding is subjected to Him by believing Him, -- but not by believing anything false, because no falsehood can be proposed to man by God, who is the truth: hence he who believes anything false does not believe God.

3. Whoever holds an erroneous view about a thing, touching the essence of the thing, does not know the thing. Thus if any one were to fix on the notion of irrational animal, and take that to be man, he would not know man. The case would be otherwise, if he was mistaken only about some of the accidents of man. But in the case of compound beings, though he who errs about any of the essentials of a thing does not know the thing, absolutely speaking, still he knows it in a sort of a way: thus he who thinks man to be an irrational animal knows him generically: but in the case of simple beings this cannot be, -- any error shuts out entirely all knowledge of the thing. But God is to the utmost degree simple. Therefore whoever errs about God does not know God. Thus he who believes God to be corporeal has no sort of knowledge of God, but apprehends something else instead of God.* Now as a thing is known, so is it loved and desired. He then who errs concerning God, can neither love Him nor desire Him as his last end. Since then the divine law aims at bringing men to love and desire God, that same law must bind men to have a right faith concerning God.

Hence it is said: Without faith it is impossible to please God (Heb. xi, 6); and at the head of all other precepts of the law there is prescribed a right faith in God: Hear, O Israel: the Lord thy God is one Lord (Deut. vi, 4).

3.117 : That by the Divine Law we are directed to the Love of our Neighbour
3.119 : That by certain Sensible Rites our mind is directed to God