As someone who is a Christian, I'll give you my opinion.
I believe that we are created with an inherent sense of right and wrong (the real reason for the story of Eden), and that there is a little of God's spirituality and ethical sense within us ("Made in His Image" spiritually, not necessarily physically).
As we live, grow and evolve mentally and spiritually, we make decisions that allow us to accept God, allow us to judge ourselves, and allow us to make decisions. All of this is tied into free will.
After death, we basically judge ourselves, I'm not so sure there's some line with a "good/bad" writing. Those who cannot accept themselves, who cannot handle the concept of God and forgiveness and a Savior, they choose to go on as they are. They make a decision that they are independent of God, they basically stop evolving spiritually because they have no further spiritual purpose. They place themselves apart from God, in "Hell". Anything that does not grow, is dying. Over time, regret, self-doubt, boredom, and lack of purpose become their own punishments, the "flames" are emotional, especially when the soul learns that there was more to do, higher planes of existence, or even reincarnation (all concepts that the Bible isn't really specific on beyond being near God in Heaven...guess we'll find out what that's all about when we die, I can wait).
I believe that Hell is the decision not to accept God. It's a place of stagnation, interaction with other hopeless souls, a place of suffering over time as the soul dies from lack of stimulation and purpose. And the crux of it: we choose to condemn ourselves based on our own decisions.
My two cents.
-SB