Nine days before Easter in 2012, the Rev. Teresa MacBain sent a letter to the congregants she had pastored for three years at a Methodist church in Tallahassee, Fla. For much of that time, she had preached the Gospel every Sunday, only to slip each Monday into tormented doubt.

Finally, she realized her faith crisis was over. She no longer believed in God. The daughter of a minister, the product of a divinity school, the enthusiastic evangelist doing the Lord’s will, she told her followers that she was resigning her pulpit.

Her first public comments, a few days before she stepped down as minister, sounded brash, as she told a convention of atheists that she would gladly burn in hell with them. Deeper inside, however, she felt more sorrow than triumph, more exile than liberation.

“After I stepped away from my ministry, I literally stepped off the cliff,” Ms. MacBain, 45, recalled in a recent interview. “I didn’t know what life would be like without a church. I was depressed. I was out there in limbo all at once. There is no community. There is no social network. The majority of friendships are gone. There is no place I can go every week where I know people and they know me.”