The word 'evangelical' used to be a tightly defined description.

If you said someone was evangelical you knew pretty much what you were getting – inerrancy of the Bible, importance of preaching, a focus on evangelism, warnings of hell and most of all – opposition to gay marriage.

Being anti-same sex marriage and evangelicalism used to be synonymous, so much so that when Steve Chalke announced he backed the change in law his church Oasis was kicked out of the Evangelical Alliance.

But now it is not so clear.

While still far from the mainstream and the overwhelming majority of self-described evangelicals are still opposed to gay marriage, there are a growing list of pastors who describe themselves as evangelical and yet support same sex couples.

Tony Campolo

The famous evangelist and pastor announced his change of position in a statement last June.

'It has taken countless hours of prayer, study, conversation and emotional turmoil to bring me to the place where I am finally ready to call for the full acceptance of Christian gay couples into the Church,' he wrote.

'Through [my wife] Peggy, I have come to know so many gay Christian couples whose relationships work in much the same way as our own. Our friendships with these couples have helped me understand how important it is for the exclusion and disapproval of their unions by the Christian community to end. We in the Church should actively support such families. Furthermore, we should be doing all we can to reach, comfort and include all those precious children of God who have been wrongly led to believe that they are mistakes or just not good enough for God, simply because they are not straight.'

Rob Bell

In a debate at San Francisco's Grace Cathedral in 2013, the author and pastor Rob Bell, already discredited by many evangelicals for his book Love Wins, gave a blanket endorsement of gay marriage.

'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 this is the world we are living in and we need to affirm people wherever they are.'

He went on to give a wholesale criticism of traditional evangelicalism and in particular its own subculture: 'I think we are witnessing the death of a particular subculture that doesn't work. I think there is a very narrow, politically intertwined, culturally ghettoised, Evangelical subculture that was told "we're gonna change the thing" and they haven't ... And we have supported policies and ways of viewing the world that are actually destructive. And we've done it in the name of God and we need to repent.'

Jim Wallis

An outspoken critic of the Religious Right and president of the Sojourners magazine, Jim Wallis reversed his stance on gay marriage in an interview with the Huffington Post in 2013.

'How do we commit liberals and conservatives to re-covenanting marriage, reestablishing, renewing marriage?,' he asked.

'I think we should include same-sex couples in that renewal of marriage, [but] I want to talk marriage first. Marriage needs some strengthening. Let's start with marriage, and then I think we have to talk about, now, how to include same-sex couples in that deeper understanding of marriage. I want a deeper commitment to marriage that is more and more inclusive, and that's where I think the country is going.'

Jen Hatmaker

One of the relatively few prominent female voices on the evangelical scene, Hatmaker received a fierce backlash when she said she thought God saw monogamous gay relationships as holy.

In an interview with Religion News Service she said: 'From a spiritual perspective, since gay marriage is legal in all 50 states, our communities have plenty of gay couples who, just like the rest of us, need marriage support and parenting help and Christian community. They are either going to find those resources in the church or they are not.

'Not only are these our neighbors and friends, but they are brothers and sisters in Christ. They are adopted into the same family as the rest of us, and the church hasn't treated the LGBT community like family. We have to do better.'

Asked if she would attend a gay friend's wedding she said it was an easy answer: 'I would attend that wedding with gladness, and I would drink champagne. I want the very best for my gay friends. I want love and happiness and faithfulness and commitment and community. Yes. That's an easy answer.'

Danny Cortez

The Southern Baptist church pastor from Los Angeles, California, announced in 2014 he is 'gay affirming' and had accepted his son's homosexuality.

'In August of 2013, on a sunny day at the beach, I realized I no longer believed in the traditional [church] teachings regarding homosexuality,' Cortez said in a letter published on Patheos blog.

'And it was especially the testimony of my gay friends that helped me to see how they have been marginalised that my eyes became open to the injustice that the church has wrought.'

He wrote that many had left his church after the announcement but those who remained decided to agree to disagree and not pass judgment.