On the subject of belief and whether or not non-belief would be a bar towards salvation, I tend to come back to Meister Eckhart who wrote something about if someone were to die and angels were to strip them of their "life" then if they were unprepared for it and in a state of disbelief about it they would not see them as angels at all but devils, the belief would indeed effect the experience itself. There is another poem about an orange man, who also happens to be pretty sectarian, who dies and goes to heaven discovering that there are papists and popes there he is very disatisfied and becomes a ghost instead, choosing to walk the earth instead because sharing heaven with those people amounts to a personal hell for him, of his own making. Its the same idea.
Most people who are admently non-believers, as opposed simply to disbelievers or unbelivers (nuanced meanings, I know), I think would hate to be in heaven or God's prescence or any kind of afterflife, dont you think? I dont see that God would want to or would have to torment anyone of that kind because God's simple "being" or "existence" would be sufficient to bother them, for eternity depending on how hard hearted they are about it.