“David Cameron and the right have tried to own the Christian vote, which is fundamentally unbiblical,” declared Anna McMullen, attending the Greenbelt festival last weekend. “Jesus and the Bible’s teaching are all about socialism, basically.”

It’s not an unusual comment to hear at Greenbelt, one of Britain’s largest Christian festivals, which has drawn crowds of between 10,000 and 20,000 for years. 

It has gained a reputation as open-minded and left of centre. This does not mean it is a hotbed of radicalism. Nonetheless, radical ideas were both present and visible. 

McMullen’s comments came after a rousing talk by Owen Jones. 

Rob Telford, a Christian who is standing for the deputy leadership of the Green Party, told me he had agreed with almost everything Jones said — until he expressed support for the Labour Party. When it came to austerity, Telford said: “Labour aren’t going to sort the issue out.” 

Similar disputes came up several times over the three- and-a-half days of Greenbelt. Christian supporters of Labour — including Suzy Stride, Labour’s parliamentary candidate for Harlow —were vocal in encouraging Christians to rally behind Ed Miliband. Others dismissed Labour as pro-cuts and pro-Trident as they gave their backing to more left-wing parties such as the Greens or Plaid Cymru. 

Of course, there were also Tory and Lib Dem supporters around, sometimes complaining of anti-government bias. 

Greenbelt is different from many Christian festivals in that most attenders oppose the government and support same-sex marriage. But at times there was a strong smell of middle-class liberalism with people talking about helping the poor in ways that sounded more like charity than solidarity. 

Thankfully, this was not always the case. Niall Cooper of Church Action on Poverty said that churches tend to be good at “rescuing people who have fallen into the river” but that they need to be challenging those who are “throwing them in.” 

Juliet Kilpin from Urban Expression believes churches should not be celebrating when they open new food banks but protesting about the fact that they need to do so. 

There were frequent debates on sexuality and gender. Evangelical singer Vicky Beeching (below),  who came out as gay just before the festival, received a standing ovation for her courage and resistance to homophobia. For the first time, Greenbelt’s main communion service on Sunday morning included a prayer for people campaigning for LGBT rights. 

Some went further. In a late-night debate, Anglican priest Rachel Mann said the church had made a “fetish” of marriage, while theologian Marika Rose suggested that polyamory could be ethical for Christians. 

Many Greenbelters go to the festival for music rather than for talk. Sinead O’Connor drew the crowds in spite of rain. Folk singer Grace Petry began her act with her anti-fascist song They Shall Not Pass. 

Satirical duo Jonny and the Baptists poked fun at Ukip, beginning with councillor David Silvester who blamed floods on same-sex marriage. “He’s the first member of Ukip to believe in man-made climate change.” 

This year’s festival was held in the grounds of Boughton House near Kettering, replacing the popular previous venue in Cheltenham. On the whole, regular festival-goers responded positively to the new site, although a number of disabled attenders argued that parts of it should have been made more accessible. 

Greenbelt is a Christian festival at which the divide is not between liberals and conservatives but between liberals and radicals. The actively radical voice is getting stronger, but it has far to go to make a big impact. 

Left-wing Christians need to speak up more loudly.