I've been reading NEARER MY GOD by William F. Buckley, in which he narrates an exchange between Arnold Lunn, the inventor of the slalom in skiing, a lifelong friend of Buckley's, and the inquisitor in a dialog in the 30's with Fr. Ronald Knox, a famous convert from Anglicanism. Lunn was an agnostic at the time (he later converted to Catholicism and was baptized by Knox), and said, along with John Stuart Mill, that "Compared with the doctrine of endless torment, every objection to Christianity sinks into insignificance."
Knox, too, said that when he himself was received into the Church, the problem of eternal punishment was the single difficulty still on his conscience. Knox accepted the teaching of the Church, but struggled with the doctrine for many years. He finally worked through His own doubts. His arguments are persuasive: eternal punishment provides a symmetry to the Christian edifice (shouldn't eternal punishment be a counterpoint to eternal bliss?); the Church could have posited simply the annhilation of the soul of the wicked--that it did not is conclusive to the existence of hell; heaven is not had for the asking, which is the way we would go if we assumed that God's mercy would always intervene between the sinner and eternal punishment.
Knox concludes his argument, however, by saying that it is certainly a part of Christian hope to pray that hell is empty and that, when asking the question whether a particular person, guilty of particular sins, are deserving hell, one must say "Well, if he doesnt' deserve hell, he won't get it. More than that, I'm not sure we can say."
Needless to say, it is a fascinating dialogue, and it raised the question about whether or not we are required to believe that there are actually souls in hell.
I want to reiterate that I certainly believe in hell, but that hell was created for Lucifer and his minions. Men can go to hell BECAUSE they can also go to heaven. But because we can envision an infinitely merciful God not wishing that any of His creation perish, but have eternal life (as THE HOUND OF HEAVEN by Francis Thompson so powerfully illustrates), it is not contrary to Faith to hope and pray that no one is in hell. Maryz, thanks for referencing Fr. Neuhaus' as one who also joins in this hope.
It's a theoretical question, of course, since none of us can answer it.
Again, I appreciate the contributions made by all.