To use the fire metaphor in my life there had always been smoldering embers. I never did fit in socially with the membership of the church, to the point that as a young man I was routinely belittled and beaten my my peers. Strange enough I could easily dismiss that behavior as the actions (and inaction by the leadership) of "men" in which God was bound by his honor to not interfere. This explanation for most of the "evils" in the world worked well as most human suffering is a direct result of human action or inaction. God not willing to interfere with the agency he had granted to "men" as a matter of divine law is a fundamental tenant of Mormonism, and most Christian belief systems. I had been taught in public school about geology, and evolution, and was able to dismiss the evidence of dinosaurs and hominids as details from the creation that we had not been told because they were not important to our eternal salvation. The time scale was the same issue, who knows how God measures time? Who said the the materials could not have been reused from some previous creation? Those were very palatable explanations to the evidence in the natural world, and that God as the author of nature, would use natural processes to bring about his great work. This all seemed very reasonable from the God paradigm. The event that blew all the ash away and ignited the flame was the dissolution of my family. For Mormons there is really only one thing that they need to worry about, and that is making more Mormons. Raising a family is the most important thing a Mormon can do and is essential to their salvation. So it is reasonable that God would not allow anything he could change to interfere with that work. This was the crux of my God dilemma, either God was good and would not allow my family to be dissolved due to things he could influence, or he had no personal involvement in anyone's life because he a) was not there, or b) did not care. You see my wife has bi-polar disorder as do many of her family, we can trace it back as far as her great-grandfather who had hallucinations and died in a state mental hospital. Due to this disorder she is to say the least unstable, one night she was hallucinating that I was going to kill her and she stabbed me. This got the state authorities involved in our family, a hell on earth in itself. They stayed involved with our family for over two years, the whole while citing that they felt that despite our compliance with their programs, we and she in particular had not made sufficient progress. This whole time I and we as a family had prayed for God to help our family, that my wife's illness would respond to treatment, or even b cured. This did not happen. The members of the wards we lived in treated us as contagious lepers, as if by even by associating with us they might get the same dysfunctions. They even tried to rationalize that we were somehow evil and had brought this upon ourselves, calling upon us to repent of whatever we had done. For a time I even believed that, but could not find anything I or any of us could have done to deserve this fate. Again the agency of men fallacy explained their behavior. The failure of divine intervention in my wife's and subsequently our family's condition, was another matter. The eventual dissolution of our family, our children taken from us and put up for adoption, was a crisis. I went into a deep depression. I felt that God hated me, and that I would be better dead. I had a plan to kill myself, actually several, and had just about resolved to carry one out. Then I had a thought, what if my underlying assumption was wrong? What if God did not exist? What if all these things were just random chance? How would the world, or all the Universe look? If God did not exist, God could not hate me, and my influence on the world was my own doing be it good, evil, or benign. Random chance seemed to fit the way the world is better than a personally involved loving God. This was the shift, the fire, the flame. It was as if those smoldering embers of doubt had been given a deep breath of air and then had gasoline poured upon them. My world became brighter, I could see things more clearly and understood deeper than I ever thought I could. Reason and observation were great tools. We left the state, found a psychiatrist who used those tools instead of telling her to take a pill and then prayed that it was the right one. Understanding evolutionary psychology helped me to understand why we do the things we do better than a creationist God ever did. As for the rest, if God is not there, then the Church is not the place to be, especially since for us it was a hostile society. And that is how I left.
Wow. This is wild. All of these answers...I grew up in central Utah. I didn't know there was such a thing as "other churches" until I was in third grade, but by the time I was in high school I knew I didn't believe in a god. After high school, I married (at 18, which was not only acceptable, but expected in my rural, conservative community) one of the only other kids I had met in the area who raised questions about the church. We moved out of state, and bounced around the country a little for a few years, and had two children. As we were growing into young adults, it became more clear on a daily basis how differently we really felt about the church we were raised in. I wanted to free myself from the doctrine and everything related to it, but when things got tough he would revert back to those ways of our youth; he would seek the spiritual answers offered by church members and officials rather than work out his issues in a realistic light. His childhood indoctrination had really done a number on him, and it was ultimately one of many reasons our marriage failed. After my car was totaled in an accident, I was broke, divorced, and unsure of what the fuck I was supposed to do. I came back to Utah, where my parents were begging me to bring my children so they could help me get back on my feet, and I came back being totally open about my distaste for religion. I've been outright about refusing to allow my children to be "blessed" or "baptized" into the church unless for some unfathomable reason they decide to do it on their own after they're adults. My grandma still asks me to join her at relief society meetings and I'm polite enough to make up a different excuse, but even she knows the truth. I am not a mormon. Or a christian. I am over it.
I was sixteen and in seminary and they were discussing who was and wasn't allowed to go to the Cellestial kingdom. Basically good people who did good deeds everyday were not going to be allowed. I guess until that point I hadn't really thought about it critically. After that it was a snow ball a gradual but never less powerful snow ball.