Thomas Aquinas

“ Now the principal object of faith is the First Truth, the sight of which gives the happiness of heaven and takes the place of faith. Consequently, as the angels before their confirmation in grace, and man before sin, did not possess the happiness whereby God is seen in His Essence, it is evident that the knowledge they possessed was not such as to exclude faith. ”

“ Now a man may possess the science of geometry as to some geometrical conclusions, and yet be ignorant of other conclusions. Therefore a man can believe some articles of faith without believing the others.
Objection 3: Further, just as man obeys God in believing the articles of faith, so does he also in keeping the commandments of the Law. Now a man can obey some commandments, and disobey others. Therefore he can believe some articles, and disbelieve others.
On the contrary, Just as mortal sin is contrary to charity, so is disbelief in one article of faith contrary to faith. ”

“ A man who obstinately disbelieves a thing that is of faith, has not the habit of faith, and yet he who does not explicitly believe all, while he is prepared to believe all, has that habit. In this respect, one man has greater faith than another, on the part of the object, in so far as he believes more things, as stated above. ”

“ Reply to Objection 3: The very fact that the signs of faith are so evident, that the demons are compelled to believe, is displeasing to them, so that their malice is by no means diminished by their believe. ”

“ Secondly, because the intellect is convinced that it ought to believe what is said, though that conviction is not based on objective evidence. Thus if a prophet, while preaching the word of God, were to foretell something, and were to give a sign, by raising a dead person to life, the intellect of a witness would be convinced so as to recognize clearly that God, Who lieth not, was speaking, although the thing itself foretold would not be evident in itself, and consequently the essence of faith would not be removed. ”

“ Consequently we must hold that the angels had faith before they were confirmed, and man, before he sinned. Nevertheless we must observe that in the object of faith, there is something formal, as it were, namely the First Truth surpassing all the natural knowledge of a creature, and something material, namely, the thing to which we assent while adhering to the First Truth. ”

“ Consequently, if the demons have faith, some men would be guilty of a sin graver than that of the demons, which seems unreasonable. Therefore in the demons there is no faith.
On the contrary, It is written (James 2:19) : "The devils . . . believe and tremble."
I answer that, As stated above (Q [1] , A [4] ; Q [2] , A [1] ) , the believer's intellect assents to that which he believes, not because he sees it either in itself, or by resolving it to first self-evident principles, but because his will commands his intellect to assent. ”

“ In the original state there was no hearing anything from man speaking outwardly, but there was from God inspiring inwardly: thus the prophets heard, as expressed by the Ps. 84:9: "I will hear what the Lord God will speak in me." ”