re is a non-Catholic who firmly believes that
the church to which he belongs is the true Church, and who has
never--even in the past--had the slightest doubt of that fact--what will
become of him?

If he was validly baptized and never committed a mortal sin, he will be
saved; because, believing himself a member of the true Church, he was
doing all he could to serve God according to his knowledge and the
dictates of his conscience. But if ever he committed a mortal sin, his
salvation would be very much more difficult. A mortal sin once committed
remains on the soul till it is forgiven. Now, how could his mortal sin
be forgiven? Not in the Sacrament of Penance, for the Protestant does
not go to confession; and if he does, his minister--not being a true
priest--has no power to forgive sins. Does he know that without
confession it requires an act of perfect contrition to blot out mortal
sin, and can he easily make such an act? What we call contrition is
often only imperfect contrition--that is, sorrow for our sins because we
fear their punishment in Hell or dread the loss of Heaven. If a
Catholic--with all the instruction he has received about how to make an
act of perfect contrition and all the practice he has had in making such
acts--might find it difficult to make an act of perfect contrition after
having committed a mortal sin, how much difficulty will not a Protestant
have in making an act of perfect contrition, who does not know about
this requirement and who has not been taught to make continued acts of
perfect contrition all his life. It is to be feared either he would not
know of this necessary means of regaining God's friendship, or he would
be unable to elicit the necessary act of perfect contrition, and thus
the mortal sin would remain upon his soul and he would die an enemy of
God.

If, then, we found a Protestant who never committed a mortal sin after
Baptism, and who never had the slightest doubt about the truth of his
religion, that person would be saved; because, being baptized, he is a
member of the Church, and being free from mortal sin he is a friend of
God and could not in justice be condemned to Hell. Such a person would
attend Mass and receive the Sacraments if he knew the Catholic Church to
be the only true Church.

I am giving you an example, however, that is rarely found, except in the
case of infants or very small children baptized in Protestant sects. All
infants rightly baptized by anyone are