Objection 1. It would seem that faith remains after this life. Because faith is more excellent than science. Now science remains after this life, as stated above (Article 2). Therefore faith remains also.
Objection 2. Further, it is written (1 Corinthians 3:11): "Other foundation no man can lay, but that which is laid; which is Christ Jesus," i.e. faith in Jesus Christ. Now if the foundation is removed, that which is built upon it remains no more. Therefore, if faith remains not after this life, no other virtue remains.
Objection 3. Further, the knowledge of faith and the knowledge of glory differ as perfect from imperfect. Now imperfect knowledge is compatible with perfect knowledge: thus in an angel there can be "evening" and "morning" knowledge [Cf. I, 58, 6]; and a man can have science through a demonstrative syllogism, together with opinion through a probable syllogism, about one same conclusion. Therefore after this life faith also is compatible with the knowledge of glory.
On the contrary, The Apostle says (2 Corinthians 5:6-7): "While we are in the body, we are absent from the Lord: for we walk by faith and not by sight." But those who are in glory are not absent from the Lord, but present to Him. Therefore after this life faith does not remain in the life of glory.
I answer that, Opposition is of itself the proper cause of one thing being excluded from another, in so far, to wit, as wherever two things are opposite to one another, we find opposition of affirmation and negation. Now in some things we find opposition in respect of contrary forms; thus in colors we find white and black. In others we find opposition in respect of perfection and imperfection: wherefore in alterations, more and less are considered to be contraries, as when a thing from being less hot is made more hot (Phys. v, text. 19). And since perfect and imperfect are opposite to one another, it is impossible for perfection and imperfection to affect the same thing at the same time.
Now we must take note that sometimes imperfection belongs to a thing's very nature, and belongs to its species: even as lack of reason belongs to the very specific nature of a horse and an ox. And since a thing, so long as it remains the same identically, cannot pass from one species to another, it follows that if such an imperfection be removed, the species of that thing is changed: even as it would no longer be an ox or a horse, were it to be rational. Sometimes, however, the imperfection does not belong to the specific nature, but is accidental to the individual by reason of something else; even as sometimes lack of reason is accidental to a man, because he is asleep, or because he is drunk, or for some like reason; and it is evident, that if such an imperfection be removed, the thing remains substantially.
Now it is clear that imperfect knowledge belongs to the very nature of faith: for it is included in its definition; faith being defined as "the substance of things to be hoped for, the evidence of things that appear not" (Hebrews 11:1). Wherefore Augustine says (Tract. xl in Joan.): "Where is faith? Believing without seeing." But it is an imperfect knowledge that is of things unapparent or unseen. Consequently imperfect knowledge belongs to the very nature of faith: therefore it is clear that the knowledge of faith cannot be perfect and remain identically the same.
But we must also consider whether it is compatible with perfect knowledge: for there is nothing to prevent some kind of imperfect knowledge from being sometimes with perfect knowledge. Accordingly we must observe that knowledge can be imperfect in three ways: first, on the part of the knowable object; secondly, on the part of the medium; thirdly, on the part of the subject. The difference of perfect and imperfect knowledge on the part of the knowable object is seen in the "morning" and "evening" knowledge of the angels: for the "morning" knowledge is about things according to the being which they have in the Word, while the "evening" knowledge is about things according as they have being in their own natures, which being is imperfect in comparison with the First Being. On the part of the medium, perfect and imperfect knowledge are exemplified in the knowledge of a conclusion through a demonstrative medium, and through a probable medium. On the part of the subject the difference of perfect and imperfect knowledge applies to opinion, faith, and science. For it is essential to opinion that we assent to one of two opposite assertions with fear of the other, so that our adhesion is not firm: to science it is essential to have firm adhesion with intellectual vision, for science possesses certitude which results from the understanding of principles: while faith holds a middle place, for it surpasses opinion in so far as its adhesion is firm, but falls short of science in so far as it lacks vision.
Now it is evident that a thing cannot be perfect and imperfect in the same respect; yet the things which differ as perfect and imperfect can be together in the same respect in one and the same other thing. Accordingly, knowledge which is perfect on the part of the object is quite incompatible with imperfect knowledge about the same object; but they are compatible with one another in respect of the same medium or the same subject: for nothing hinders a man from having at one and the same time, through one and the same medium, perfect and imperfect knowledge about two things, one perfect, the other imperfect, e.g. about health and sickness, good and evil. In like manner knowledge that is perfect on the part of the medium is incompatible with imperfect knowledge through one and the same medium: but nothing hinders them being about the same subject or in the same subject: for one man can know the same conclusions through a probable and through a demonstrative medium. Again, knowledge that is perfect on the part of the subject is incompatible with imperfect knowledge in the same subject. Now faith, of its very nature, contains an imperfection on the part of the subject, viz. that the believer sees not what he believes: whereas bliss, of its very nature, implies perfection on the part of the subject, viz. that the Blessed see that which makes them happy, as stated above (Question 3, Article 8). Hence it is manifest that faith and bliss are incompatible in one and the same subject.
Reply to Objection 1. Faith is more excellent than science, on the part of the object, because its object is the First Truth. Yet science has a more perfect mode of knowing its object, which is not incompatible with vision which is the perfection of happiness, as the mode of faith is incompatible.
Reply to Objection 2. Faith is the foundation in as much as it is knowledge: consequently when this knowledge is perfected, the foundation will be perfected also.
The Reply to the Third Objection is clear from what has been said.
Source: Summa Theologica (New Advent)