I turned my back on Christianity some ten years back, when I realized that organized religions were the 2nd greatest obstacle to world peace (next to greed). Before that I had stayed, despite my inability to believe much of the Jesus story or any of the narratives regarding God acting in history, because the congregations I belonged to really were a force for good in their communities.

Fundamentalism has predictable characteristics, including authoritarianism, intolerance for dissent or doubt, self-view as an embattled minority trying to purify the church, paternalism/misogyny, revisionist views of history, and mistrust of science. These tend to be the same, regardless which religion it's attached to. Fundamentalist Christians have far more in common with fundamentalist Muslims than either has with the mainstream or liberal branches of their religions.

Reading I would recommend: either of 2 books by Episcopal Bishop John Shelby Spong: "Rescuing the Bible from Fundamentalism" and "Why Christianity Must Change or Die."