Bestselling book author and former pastor Rob Bell is at it again.

After his book Love Wins was criticised by evangelists for challenging traditional ideas of hell, Bell and his wife Kristen appeared in Oprah Winfrey's "Super Soul Sunday" show and challenged the church's traditional position on marriage according to the Bible. 

"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 co-workers and neighbors and they love each other and just want to go through life with someone,"  Rob stated.

His wife Kristen added: "There are churches who are moving forward and there are churches who are almost regressing and making it more of a battle."

"Whoever you are, gay or straight, it is totally normal, natural and healthy to want someone to go through life with. It's central to our humanity. We want someone to go on the journey with," Rob stressed.

The couple appeared on the show to talk about their new book, The Zimzum of Love: A New Way of Understanding Marriage, in which they share their experiences on how to improve relationships with partners.

Rob Bell is one of the most polarising figures in Christian faith. During his time as Mars Hill Bible Church pastor, he was one of the key figures in the evangelical movement and Mars Hill was one of the fastest growing congragations in the US.  He was named one of 2011's Time's Most Influential People in the World.

In the last few years, however, he has gradually departed from traditional Christian beliefs and begun to actively criticise the conservative view for being restrictive, and for, in his view, failing to shape people into loving and compassionate beings. In turn, he has been shunned by conservative Christians for his statements.

Still, he continues to enjoy a huge following and his profile is on the up once again after he partnered with Oprah Winfrey's Network for The Rob Bell Show, where he discusses problem and offers perspectives on life and faith.

This is not the first time Bell spoke about gay marriage as he also commented on the issue in an interview with mLive during his book tour for What We Talk About When We Talk About God in 2013.

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

In another interview with Odyssey Networks for the same tour, he even went so far as to say that it is God who is lighting the path to acceptance.

"We need to love affirm and all of us, together, work on the real problems we have in the world. You are seeing God pulling us forward into a greater realisation that we need more love, more fidelity, more monogamy, more people committed to each other. Its not good for people to be alone so this is a huge moment when I thing old way of seeing things does not work, it causes so much pain and God is inviting us to see things in new ways and we need to say yes and we need to step into the future," he said.