by Susan Dondaldson James, ABC News
In his Nashville Christian church, Timothy Kurek was taught the lesson of God's wrath in the Biblical story of "Sodom and Gomorrah," and he believed that homosexuality was a sin.
"You learned to be very afraid of God," said Kurek. According to the preachings of his church, "The loving thing to do is to tell my friend who is gay, 'Hey, listen, you are an abomination and you need to repent to go to heaven.' I absolutely believed in that lock, stock and barrel."
So devout was Kurek as a teen that friends' parents would often call him to set their kids straight if they misbehaved or broke what they believed to be God's law.
"I would be the one on the phone until four in the morning, asking them to repent for their sins," he said.
But about four years ago, when a lesbian he knew from karaoke night confided to him that her parents had disowned her when she came out, Kurek felt that he failed her.
"I feel God really kicked me in the gut," he said. "She was crying in my arms and instead of being there for her, I was thinking about all the arguments to convert her."
Kurek's reaction ate away at him, and he wondered what it felt like to be gay and so alone. So even though Kurek identifies as straight, he embarked on what one religious writer called "spiritual espionage." He would live like a gay man for a year.
"It finally clicked," he said. "I needed to empathize and understand."
Now 26 and no longer homophobic, Kurek writes about his journey -- one that included hanging out in gay bars and facing the disappointment of his family and rejection of his friends -- in his memoir, "The Cross in the Closet."
He chose today, National Coming Out Day and LGBT National History Month, to launch book sales and has pledged to give some of the proceeds to a charity that helps LGBT youth who are homeless.
He says he hopes to change minds, not just in the Christian community but in the LGBT one as well, and to bridge the divide in the debate over gay rights.
Some experts say his attitude reflects those of other young Christians.
Dr. Jack Drescher, a New York City psychiatrist who has an expertise in LGBT issues, says the younger generation is less anti-gay than some of their elders.
"The question of 'love the sinner and hate the sin,' is an idea they are being forced to question," he said. "Some of the sound bites [on homosexuality] are not working so well for the younger generation ? Condemnation has a human cost."
Kurek had been homeschooled by parents who never taught him to shun or hate gay people and who admitted they had wrestled with the church's teaching on homosexuality.
He said he had always wanted to write a book, but never finished his studies at the Christian Liberty College in Lynchburg, Va.. But Kurek had kept a daily journal for months, and it was "beginning to read like a book."
By 2009, the idea to go undercover, as a way of documenting and learning about homophobia, was born. For six months he plotted and planned. "I had to make sure the timing was right," he said.
But one day, sitting in a café in a part of Nashville where the gay bars and Christian hang-outs intersect, Kurek had his first confrontation. While reading a gay-themed book, he became aware of the "snickers and sneers."
"A guy came up to me when he saw the cover and said, 'You know that is fundamentally false -- you can't be gay and Christian,'" said Kurek, who responded, "I am gay and I love God."
The project to become gay had begun for real.
Only three people knew the truth, and he needed them to carry out his audacious project: his closest friend, an aunt and Shawn, a gay friend whom Kurek also met at karaoke night.
"My aunt is my mom's best friend and is more liberal in her faith," Kurek said. "She was also able to listen to what my family was saying behind my back ... If my mom went off the deep end, I needed to know."
After a week, he realized he also needed help warding off the advances of gay men.
Kind-hearted Shawn, whom Kurek described as "a big black burly teddy bear," became his "pretend boyfriend."
"I needed protection to keep me balanced and teach me the nuances of gay culture and how they flirt, and to give me an excuse when guys hit on me," said Kurek.
For credibility, Kurek learned to hold hands and embrace.
But most of all, Shawn was the "first gay person that I let into my heart," said Kurek. "He was totally there for me through emotional turmoil ... I trusted him.
"He knew I was straight and he didn't take it too far -- and he taught me not to be afraid."
Eventually the initial "revulsion" disappeared, according to Kurek.
The hardest part was facing his parents, who were divorced.
"There was always an elephant in the room," he said. "I snooped in my mother's journal one day after I had come out and she'd written, 'I'd rather have found out from a doctor that I had terminal cancer than have a gay son.'"
With his friends, "the thing that struck me most was the isolation," he said. "Before I came out as gay, I had a very busy social life. After I came out, I didn't hear from 95 percent of my friends."
In his book, Kurek stays away from theology. "I want this seen as a people issue," he said. "When we are shunning people, we are shunning Fred and John and Liz and Mary. These are human people."
"In the end it was a book about prejudice, not a book about being gay."
The response to his experience has been positive, according to Kurek. His mother is now supportive of LGBT rights.
Rev. Connie Waters, a protestant minister and LGBT ally from Memphis who met Kurek online when he was questioning his church's view of homosexuality, said she was "proud" of him.
She never encourages her parishioners to lie, but in the case of Kurek's undercover project, it served a "greater purpose."
"For him to appreciate what others went through was essential for him to experience a small part of what those who are LGBT have had to live through to be safe for many years," said Waters.
"The transformation in him was life-changing," she said. "It's what you hope for -- the goal of the Christian walk of faith. It's enough for me that he transformed, but if others learn from him, what an extra blessing that is."