WATCH: Oprah Asks if Christian Support for Marriage Equality Is 'Moments Away?'

Christian churches are "moments away" from showing unfettered support for marriage equality, evangelical minister and author Rob Bell told media mogul Oprah Winfrey Sunday.

Bell and his wife, Kristen, appeared on an episode of Oprah's Super Soul Sunday television series to talk about relationships and marriage, which Rob Bell called "an adventure in which you actually get to create and cocreate a life."

Just past the 29-minute mark, the show introduced the topic of marriage equality by showing a clip of Kristen Bell reading an except from The Zimzum of Love: A New Way of Understanding Marriage, a book she and her husband wrote and which was released in fall 2014.

"Marriage -- gay and straight -- is a gift to the world because the world needs more, not less, love, fidelity, commitment, devotion and sacrifice," she reads. The camera then cuts to the Bells sitting with Oprah, who lauds them for specifically including gay marriage and then starts a discussion about the issue.

"One of the oldest aches in the bones of humanity is loneliness," Rob Bell said. "Loneliness is not good for the world. And so whoever you are, gay or straight, it is totally normal, natural and healthy to want somebody to go through life with. It's central to our humanity. We want someone to go on the journey with."

"When is the church gonna get that?" Oprah asked.

"We're close," Rob Bell said, with his wife adding, "I think it's evolving."

"Lots of people are already there," Rob Bell said. "We think it's inevitable, and we're moments ..."

"Moments away from the church accepting it?" Oprah asked.

"Absolutely ... I think culture is already there, and the church will continue to be even more irrelevant when it quotes letters from 2,000 years ago as their best defense. When you have in front of you flesh and blood people who are your brothers and sisters and aunts and uncles and coworkers and neighbors, and they love each other, and they just want to go through life with someone," Rob Bell said.

Indeed, some Christian denominations have already embraced marriage equality. The Evangelical Lutheran Church in America and the United Church of Christ, for instance, allow clergy to perform same-sex marriages. Several other denominations, including the Episcopal Church and the Presbyterian Church (USA) offer "blessings" for same-sex unions and are voting on whether to recognize these unions as marriages, on an equal footing with heterosexual marriages. Still, opposition remains strong in the Roman Catholic Church, in fundamentalist Protestant denominations, and even middle-of-the-road bodies such as the United Methodist Church.

Founder of the 10,000-member Mars Hill Bible Church in Michigan (no relation to the similarly named group of churches in the western U.S.), Rob Bell left the helm of the church in 2011 (the same year Time dubbed him one of the most influential folks in the world). He's remained in the public eye, and in 2013 he stated his unequivocal support for marriage equality.

"I am for marriage. I am for fidelity. I am for love, whether it's a man and woman, a woman and a woman, a man and a man. I think the ship has sailed and I think the church needs -- I think this is the world we are living in and we need to affirm people wherever they are," he said.

Bell's spiritual/self-help series, The Rob Bell Show, premiered on Oprah's OWN network in December.

Watch the Super Soul Sunday episode: