I like the question, though disagree with the answer. A 'Satan'? Not really, no. A hell? Yes. However, my opinion of the afterlife is what you make of it, as many speak of life. But, if you live life consumed by material gains, by other things that don't influence a positive life, I believe you'll find yourself in a hellish afterlife, still consumed by things that hold little, if any, importance. This is why this entire conversation is important to me. Because without the nourishment of our souls and our very thought processes, we may find ourselves in our own personal hells. To put it best, if you haven't seen 'What Dreams May Come', I feel that holds a very real sense of Heaven and Hell, and how it isn't so much a struggle between God and Satan as it is what we make of ourselves.
But, I do believe good and evil exist. I just don't believe God and Satan have much of anything to do with it.