Here is an interesting quote from an article by Tim Keller called The Importance of Hell
Hell is therefore a prison in which the doors are first locked from the inside by us and therefore are locked from the outside by God (Luke 16:26.) Every indication is that those doors continue to stay forever barred from the inside. Though every knee and tongue in hell knows that Jesus is Lord (Philippians 2:10-11,) no one can seek or want that Lordship without the Holy Spirit (1 Corinthians 12:3.This is why we can say that no one goes to hell who does not choose both to go and to stay there. What could be more fair than that?
Read the whole thing here