When one thinks of Hell as a place where flames lick the feet of sinners and where the devil torments you, then one is thinking of Hell as pop culture has dictated it. While it is true that this vision of Hell does have a basis in religion, that basis derives from the Book of Enoch, which is considered a heretical book by most of Christianity. For centuries, the book (written before Christ) was forgotten until Dante resurrected it. Nowadays, people with only a shallow understanding of religion accept it as a valid description of Hell whereas no theologian would.
Hell is not a place. Rather, it is a state of self-exclusion from God. From Pope John Paul II:
The images of hell that Sacred Scripture presents to us must be correctly interpreted. They show the complete frustration and emptiness of life without God. Rather than a place, Hell indicates the state of those who freely and definitively separate themselves from God, the source of all life and joy.
Of course, no one explains it better than Mr. Stephen Colbert:
So Hell is not a place. It is the absence of God's love, and it is one's rejection of God's love that sends one to this state of being. Does this mean that atheists go to Hell under Christian teaching? The acceptance of God's love is not merely a belief in God; if that were true, then morality would be inconsequential. The acceptance of God's love is living a life according to the teachings of Jesus Christ. That means a kindness toward others, a willingness to put the needs of others over one's own needs, and an overall charitable nature. Loving God and accepting God's love is loving others and loving that which He has created (i.e., treating the Earth with respect). The belief in God does not necessarily enter that paradigm.
