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?