Consider the following word from Jesus:
Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but only the one who does the will of my Father who is in heaven (Mt 7.21).
If we were to do a strict logical analysis of this verse, we'll find that it predicts the eventual damnation of some. After all, to say that not everyone who says 'Lord, Lord' will be saved implies that there are some who do say 'Lord, Lord,' and yet won't be saved. Consider the following analogous example: not every student will graduate. That seems to imply that there are some students who will not graduate!
Let's consider this from the point of view strict predicate logic:
Not everyone who says to me, 'Lord, Lord' will enter the kingdom of heaven.
We might formalize this as:
~ (x)(Fx -> Gx)
where Fx = x says to Jesus 'Lord, Lord'; and Gx = x will enter the kingdom of heaven. This logical sentence says: it's not the case that for all x, if x says to Jesus 'Lord, Lord,' x will enter the kingdom of heaven. And of course, that sentence also implies this:
∃x(Fx & ~Gx)
This says that there is at least one x such that x says to Jesus 'Lord, Lord,' and x will not enter the kingdom of heaven, i.e. x will be damned.
Taken from a strictly logical point of view, then, it would seem that Jesus' statement straightforwardly entails that some persons will be damned. But now consider the following question: can we take this entailment as establishing with dogmatic certainty that some persons will therefore be damned? In other words, can we therefore know that some persons will be damned?
No, I think not, because it seems to me that texts and statements such as these of Jesus' have a different rhetorical purpose than a mere statement of fact. In other words, Jesus is trying to do something with these words: specifically, he is trying to motivate people to true repentance and to obedience of his commandments, precisely so that they will not be damned and excluded from the kingdom of heaven.
Suppose only a handful of people exist, and Jesus is speaking to all of them about the future judgment. He tells them, Not everyone who says to me, 'Lord, Lord' will enter the kingdom of heaven, but only the one who does the will of my Father who is in heaven. This statement, analyzed logically, implies that at least one of our handful of people will be lost. But imagine that everyone takes this warning to heart, and their words are backed up by true obedience; they live in true faithfulness, and none of them are lost -- they are all saved in the end.
Is such a scenario possible? Would Jesus' words have been nullified? Did he turn out to be a liar? It seems to me such a scenario is eminently possible, that Jesus' words would not have been nullified, and that he clearly would not have been a liar. The point of his making that statement in the first place was to motivate obedience, not to provide an infallible prediction of the final state of some persons or other. His words, their explicit logical form notwithstanding, are primarily and essentially an exhortation and a warning, not a historical prediction. It may be precisely because Christ spoke in that way that no one turned out to be lost; if he had not made the threat, it may be that some persons would have limited themselves to words and not to true deeds, and thus would have secured their own damnation.
This is my general point about the biblical texts which threaten damnation and seem to predict it for at least some persons: these texts, taken by themselves, do not provide any dogmatic certainty about the eventual damnation of some. Why is that? Because they are evidently (at least to me) aimed at motivating repentance; their purpose is precisely to move people away from damnation and to salvation through a threat. We do this all the time. I tell a person who is baiting an angry dog: "You're going to get hurt." Strictly speaking, my statement is a prediction about a future state of affairs; and yet that's clearly not what I'm trying to do when speaking those words -- rather, I am trying to prevent that state of affairs from obtaining precisely by telling you that you are headed towards it.
The Catechism of the Catholic Church says the same thing in its discussion of the New Testament's clear warnings about the existence and eternity of hell:
The affirmations of Sacred Scripture and the teachings of the Church on the subject of hell are a call to the responsibility incumbent upon man to make use of his freedom in view of his eternal destiny. They are at the same time an urgent call to conversion (CCC §1036).
This is the point of the hell texts in the New Testament: warning people about the reality and possibility of damnation precisely so that it is avoided through repentance and true faith. Their logical form is not always a true indication of their proper interpretation, and it is universally accepted that we often do more with our words than merely make logical subject-predicate affirmations about real things in the world.