Psychologists call it "intrapsychic phenomenon." Mathematician and Catholic philosopher Blaise Pascal could describe the exact moments: Monday, Nov. 23, 1654, from 10:30 p.m. to 12:30 a.m.
St. Augustine describes it as a voice from a "neighboring house ... as of boy or girl, I know not, chanting, and oft repeating, 'Take up and read; Take up and read.'"
Religious conversion can be dramatic or intimate and small, just a change of heart.
Science has tried to quantify and understand the experience that is often described by those who have experienced it in deeply felt language.
Psychologist L.R. Rambo, in "Understanding Religious Conversion," divides the experience into seven steps: context, crisis, quest, encounter, interaction, commitment and consequences.
But often at the heart of conversion stories are powerful tales of dramatic change.
Alison Schaefer converted from Judaism to Christianity.
Schaefer was born in England to an Orthodox family in 1949. Her first marriage was to a non-Jew, and they moved to Benton, Ky., where she worked at the local radio station.
The station had preachers who spoke on the air every day, and a few inquired about where she went to church, she said. She recalls several being surprised to learn she was Jewish.
After she had her first child, a daughter, she needed a baby sitter. The sitter was Jan Rudolph, to whom Schaefer attributes her conversion. Rudolph also became Schaefer's very dear friend.
Schaefer said Rudolph, who died at 43 of multiple sclerosis, was kind to her for no apparent reason. "I wasn't used to that," Schaefer said. She recalls Rudolph believing that she had been put on the earth to lead Schaefer to Christianity.
Rudolph's son Jason said his mother "was a joyful person, very positive, and I believe now that attitude was directly related to her faith. She was extremely upbeat about most situations, e ven the health issues she was having.
"She knew that she was where she was for a reason; she might not understand why, but she knew it was in God's control, and that was good enough for her."
The memory of Rudolph still touches Schaefer deeply. She says Rudolph lived her faith more than preached it.
"She didn't get in my face," she said. "I saw the light of God shining in her."
Schaefer and Rudolph went to a Baptist church, "where they preached heaven and hell," which was different from Schaefer's Jewish experience. But she said she found the church members "so sw eet, so kind, and I needed the family" that she found in that church community.
Schaefer describes the moment of her conversion: "I woke up in bed one morning, and you could say it was God talking to me. He said, 'Why can't you believe in Jesus?'"
That was the moment when Schaefer found "a personal relationship and faith in God," that she had been lacking. She converted to Christianity in 1976 in that little Baptist church in Western Kentucky.
Schaefer's family was disappointed by her conversion, she says, but it did not divide them. As her parents grew older, they moved to be near her.
When her father died, Schaefer wanted to be respectful of his life and find a rabbi to lead the funeral. She found one in Knoxville, "a peach of a guy," to conduct the service.
"He was a wonderful man of God" who led the graveside service and taught Schaefer's Christian friends about Jewish rituals, like sitting shiva, the custom of mourning a loved one for seven days.
As Schaefer has learned about Christianity, she has enriched her knowledge of Judaism. She believes that her study of the Old Testament has taught her that Jesus came for "the Jewish people and everyone else. ... Many Jewish people have the personal relationship with God that I was missing" but found in Christianity.
Schaefer now attends First Christian Church in London, Ky., where she has embraced her belief that Christianity taught her to "bloom where you are planted and that God is in charge."