The Evangelical concept of hell is probably the biggest reason I lost my faith. Even at 16 years old, I couldn't square it with other Christian teachings. For me, the process started not with a play but a film, "A Thief in the Night," which was popular in churches in the 1970s and which I saw when I was 10. At the time, I accepted the scenes of hell unquestioningly. I internalized a lot of fear and and a sense of fundamental —I'm not sure how to put this —despair or resentment about the state of human existence given a God inclined to vengeance and eternal torture.
It wasn't until I was 16 that I started putting puzzle pieces together. The same religion that insisted most humans ever born suffer forever in hell also insisted on things that could not possibly be true, like a literal Noah's flood, a five or six thousand year old universe, etc. That's when I realized much of it didn't just feel untrue, it was so irrational it could not be true. Even the concept of intercessory prayer had been bugging me philosophically, because of the problem of omniscience. (Not even an all powerful God should be able to change a future he already knows down to the last detail. Waving the problem away with the magic words of "God moves in mysterious ways" was unhelpful.)
So, with a huge sigh of relief, putting aside tons of fear and despair, I just let it all go. I stopped trying to force myself to believe in impossibly contradictory things. Belief fled in that instant.
I soon found that returning to belief was impossible. I could not force myself to hold ideas together that wanted, on their own, to fly apart.
Had I known any progressive Christians at the time, or if I'd access to progressive theology, I might have ended up retaining some sort of faith, but Spong was not yet enjoying his hey day of popularity and even Mainline Protestant leaders were pretty reluctant to openly question traditional beliefs.
So I didn't look back.