Continuing our discussion of salvation by habitual faith, the question we now need to address is this: While infants can be saved by habitual faith, is it ever possible for an adult to have this?
The answer is yes. How do we know this? Consider the following case: An infant that belongs to an atheist, is baptized secretly by a Catholic nurse at the hospital. Thus, the child is justified and possesses the habits of faith, hope, and charity. Suppose the child grows up never hearing of God and Christ and the Church. What happens to the child upon reaching the age of reason?
Since the Child has no knowledge of God, Christ, or the Church, he cannot make an act of explicit faith in them. On the supposition that explicit faith is absolutely necessary for the state of justification, there are three possibilities. Either the child can 1) continue after reaching the age of reason in the state of justification without any act of explicit or implicit faith, or 2) the child must necessarily commit a mortal sin and lose the state of grace, or 3) the child must receive a divine revelation of the truths which he must believe explicitly in order to remain justified.
It is clear that position number 2 cannot be correct, for there is no such thing as a "necessary" mortal sin. A sin that is "necessary" is not a sin. Hence opponents of position number 1 are forced to take position number 3. This third position, aside from the fact that there is no special reason for upholding it, is unreasonable.
Why? There have been many documented cases in which people have admitted to baptizing children of unbelieving parents without them knowing, sometimes even doing this over a long period of time (in the case of the hospital nurse). There are almost certainly far more cases that are not known. Hence, if the third position was correct, it would be almost certain that there would be cases of children having divine revelations when they reached the age of reason. But we do not have this evidence. Thus, the third position is wrong, and the first one must stand.
Furthermore, even in the case of someone who is not baptized, it is not unreasonable to believe that God could infuse Charity into a person who does not have a bad will, even if they have no explicit knowledge of Him. The reason for this is that mortal sin is the only thing contrary to Charity; hence, since it is not necessary for a man to commit a mortal sin, it will be possible that the man not commit a mortal sin, and not have his will directed towards mortal sin.
Someone might object, the cases are different, because the man who is baptized is already sanctified, hence since he does not have to commit a mortal sin, he can remain in the state of grace. However, since the man who is not baptized has original sin, doesn't this mean that his will is turned away from God, and so God cannot infuse charity into such a man.
This is false; the disposition that prevents the infusion of charity into a man is when the man either actually seeks after some temporal good in such a way as to prefer that good to God himself, or he has a disposition in himself such that if the opportunity arose, he would prefer that good to God. However, a man after committing a mortal sin may repent in such a way that he would no longer place another creature above God, while at the same time not placing his end in God. Hence he may be in the state of mortal sin, yet not have a disposition which prevents God from infusing Charity in him.
This can be manifested from the Sacrament of Confession. A man need not have perfect charity to receive the sacrament; if he commits a mortal sin, and then has imperfect contrition only, he will be in the state of mortal sin, and nevertheless he is able to receive the sacrament, by means of which God infuses charity into him.
This should explain why St. Thomas can say universally that a child attaining the age of reason is able to be sanctified from sin, regardless of his state of knowledge. Since the child is able to turn away from the good which is completely contrary to the good of reason (avoid committing a mortal sin), then God is able to infuse charity within him, even if he has not act of faith.