Summa contra Gentiles1.7 Chapter VII. That the truth of reason is not in opposition to the truth of the Christian faith

Now though the aforesaid truth of the Christian faith surpasses the ability of human reason, nevertheless those things which are naturally instilled in human reason cannot be opposed to this truth. For it is clear that those things which are implanted in reason by nature, are most true, so- much so that it is impossible to think them to be false. Nor is it lawful to deem false that which is held by faith, since it is so evidently confirmed by God. Seeing then that the false alone is opposed to the true, as evidently appears if we examine their definitions, it is impossible for the aforesaid truth of faith to be contrary to those principles which reason knows naturally.

Again. The same thing which the disciple's mind receives from its teacher is contained in the knowledge of the teacher, unless he teach insincerely, which it were wicked to say of God. Now the knowledge of naturally known principles is instilled into us by God, since God Himself is the author of our nature. Therefore the divine Wisdom also contains these principles. Consequently whatever is contrary to these principles, is contrary to the divine Wisdom; wherefore it cannot be from God. Therefore those things which are received by faith from divine revelation cannot be contrary to our natural knowledge.

Moreover. Our intellect is stayed by contrary arguments, so that it cannot advance to the knowledge of truth. Wherefore if conflicting knowledges were instilled into us by God, our intellect would thereby be hindered from knowing the truth. And this cannot be ascribed to God.

Furthermore. Things that are natural are unchangeable so long as nature remains. Now contrary opinions cannot be together in the same subject. Therefore God does not instil into man any opinion or belief contrary to natural knowledge.

Hence the Apostle says (Rom. x. 8): The word is nigh thee even in thy heart and in thy mouth. This is the word of faith which we preach. Yet because it surpasses reason some look upon it as though it were contrary thereto; which is impossible.

This is confirmed also by the authority of Augustine who says (Gen. ad lit. ii): That which truth shall make known can nowise be in opposition to the holy books whether of the Old or of the New Testament.

From this we may evidently conclude that whatever arguments are alleged against the teachings of faith, they do not rightly proceed from the first self-evident principles instilled by nature. Wherefore they lack the force of demonstration, and are either probable or sophistical arguments, and consequently it is possible to solve them.