In conjunction with a previous post on "why people choose conservative religious paths", I want to offer my thoughts (and that's all they are----thoughts, speculations, brainstorming, based on my personal experience) about why people reject conservative religious paths.
1. They are hurt and angry. They are hurt and angry about abusive authority figures, about being "lied to" by authority figures about religious doctrine, about being forced to attend religious services as children, about apparent or real hypocrisy of religious people, about abusive doctrine or doctrine which excludes the Other.
2. They have learned more about religious history and the questionable behavior of early church leaders, about the scientific process and its lack of importance to conservative religion, about themselves and their tolerance for supernatural doctrine.
3. They have redefined God and no longer accept the definition put forth by conservative religious doctrine.
4. They find a more appealing alternative, preferring to spend Sunday/Sabbath in secular activities.
5. They grew up non-religious and have never seen themselves as needing a spiritual part of their lives.
6. They are rebelling against parental values, for any number of reasons.
7. They marry a person who is not conservative in his/her religious path.
8. They have grown beyond the teachings of their early experience and find that they are unable to go back to those teachings.
For me, who grew up in a conservative home, the turning point was going to Denver as an American Baptist Home Missionary and working in a church-supported community center in the inner city. It was so clear to me that what people needed there had less to do with Jesus and more to do with food, rent, and health care. My early Christianity seemed to be more "about Jesus" than "of Jesus' teachings".
I never did feel angry about what I was taught as a child. My parents were loving and not dogmatic, even though they were very conservative. They had lots of anguish over the UU path I chose, but they had faith in me, as well as God, and I think they did a lot of praying that God would care for me.
I married into Unitarian Universalism, but I had morphed a great deal in that direction before I ever met my husband. And I needed to be in a religious community. That's one thing that growing up Baptist did for me: I could see the value and importance of a faith community and I knew I needed it.