So many tell themselves that even though they are committed to breaking one or more of the Commandments and have no intention to repent, that they still believe in Christ, and that it is this belief which will surely save them at the Judgment. Christ, they say, will condemn no one who is a believer. This is a huge blunder, spoken of as such often by Christ Himself (cf.Matt.7:21-23). It is not simply a mistake in itself, but the faith that these people claim to have is not in the Christ of the Gospels, but in a false Christ who is their own pathetic illusion.
Speaking of such people, St. John Chrysostom (c.345-407) says: "Badness of life is a mischief to (faith in) the doctrine of the Resurrection, to that of the immortality of the soul, to that of the Judgment; many other (false doctrines), too, it draws to itself: fate, necessity, denial of Providence. For the soul being immersed in numberless vices, by way of consolation to itself tries to devise these, that it may not be pained in having to reflect that there is a Judgment, and that virtue and vice lie in our power." (Homilies on the Acts of the Apostles, hom.47: cf. also Homilies on Timothy, hom.5 on 1 Tim.1:18-19).
St. John is making a simple but incisive point here. A fall into commitment to sin leads not just to unbelief, but into unbelief in a particular sequence. The sinner does not enter into unbelief by first denying the Virgin Birth, the Eucharist, or the miracles of Christ. He first denies Christ's Resurrection, immortality, Judgment. And of these three, St. John makes it clear that the first to go out the window is faith in a coming Judgment as Christ described it. Faith in Judgment as Christ described it is first thrown out "by way of consolation," so that they "may not be pained in having to reflect that there is a Judgment" of this kind.
The first point that the unrepentant sinner denies, telling himself that this has nothing to do with faith, is that repentance is absolutely necessary for salvation. What he thereby denies is not merely a real part of faith. It is the very heart of the faith, at the heart of the Revelation that Christ delivered.
After the unrepentant sinner has denied the Gospel teaching of the Judgment, his belief in immortality of any kind, including the Resurrection of Christ, also begins to erode. Then comes unbelief in the form of the acceptance of fate and necessity, and the denial of Providence, denial that virtue and vice lie in our power. Everything is excused. No one can do otherwise than what he does. Then the disease of unbelief gradually spreads to the other items of faith, so that by the time the unrepentant sinner finishes, though he stills claims to believe, he in fact scarcely believes anything taught by the Gospels and by the Christ of the Gospels.
Five different times in the Gospel of St. Matthew, Christ speaks of the fact that the damned will be "weeping and gnashing their teeth" after the Judgment. One of the things that the damned will see that causes them to do this is that the faith that they thought they had, and which they had counted upon as a protection on Judgment Day, was itself only a grotesque illusion..
The whole of Christianity is a unity in many ways. One of these is that repentance tends to go with true faith, and that unrepentance tends to go with or leads swiftly to....unbelief. There are, it is true, some people who are unrepentant in sin, but who still have true faith. But not many. If they do not use their faith to help them repent quickly, they will find, sooner or later, that their faith has disappeared, without their knowing it, and that this itself will have made them even less able to see the need for repentance.