Protesters earnestly hand out leaflets and engage in heated discussions with passers-by. Pretty standard for Greenbelt, you might think. Or, at least, you'd think that if you didn't really know Greenbelt. If you thought it was full of angry picket types, all liberal activism and lack of sense of humour. It's not like that, really. Greenbelt is Christian in the fullest sense possible: not just in the profession of faith, but in action, in attitude and in effect.

The protesters were objecting to the launching of a UK response to the Kairos Palestine document called Time for Action. Christian Zionists, they had come, some said, from as far away as Wales to demonstrate against what they saw as an attack on Israel by an heretical festival. They stood outside and argued and leafleted and did as their consciences dictated. But inside the festival, on Sunday as the document was being launched, a Jewish American signatory to Time for Action reminded the gathered crowd of well-wishers, Amos Trust supporters, Embrace the Middle East followers and activists that the people outside were not Israelis, not the board of Jewish Deputies, but Christians. And he suggested that, as Christian Zionism has long propped up support for Israeli actions regardless of their legality or morality, bringing justice to the Holy Land was a Christian issue, and that those Christians outside the gates would have to be engaged.

What could be more Christian than a call to go to those beyond our conceptual, political and theological walls and calling them in, calling them to repentance, recognising that without them we will all be poorer? What could be more Christian than, in the name of Jesus and in the spirit of the prophets, calling followers of Christ to speak boldly on behalf of both the body of Christ as it suffers and those not in the body, who God also loves? What could be more Christian than asking these things in the knowledge that they will result in anger and in vilification?

Among some Evangelicals, Greenbelt has a funny old reputation. And at times you can see why. The Christian festival with not just non-Christians on the bill, but the theologically suspect and the spiritually 'other'.

As I scrolled through social media over the weekend, I saw pictures from another Christian event happening at the same time, no doubt with motives as pure and love of God as centrally placed in its direction. Friends I love and respect were there. But the pictures of crisply clad young people standing with arms raised before a stage-designed cross and a beautiful worship leader failed to move me. I could hear the perfectly played triumphalist songs and in my mind I could hear the sermons doing the much needed work of building boundaries and spiritual identity in young people who are daily surrounded by a sea of postmodern relativism. It's important work, but it does nothing for me and would doubtless do little for many of the Greenbelt crowd. For the Palestine, tax, poverty, sexual violence, gender equality, LGBT equality, pacifist and other justice activists, or for the misfits, post-Christians and thinkers who find they are no longer stretched or moved by the same old theology, the same old worship.

Greenbelt may be different from an Evangelical worship festival, but it is undeniably, undoubtedly and gloriously Christian. Worship and prayer in their most emergent and most traditional expressions (including and encompassing mainstream evangelical anthemising) take up much of the bill, from the contemplative and liturgical to approaches that soak up all our culture's creativity and inject it into the sacramental and the spiritual. Les Mis Mass. Goth worship. The wonderfully named and beautifully realised 'U2charist'. Hymns are sung in the Jesus Arms beer tent over a pint. Communion on Sunday affirms women and the world's poor before the kyrie is sung and the bread that festival-goers have baked over the weekend is broken and consumed alongside the cup. A grandstand full of people sing in harmony for the joy of it, and the songs they sing are hymns to Jesus Christ and through artworks and music, dramas and talks, eyes fill with tears as hearts are moved to metanoia after kairos. The Holy Spirit is at Greenbelt this year, have no fear.

Yes, Marx and Malcolm X are occasionally referenced in talks. Yes, drag artists on segways cavort amusingly  with quickly accumulating crowds. Yes, feminism, liberation theology and post-Christian thinking are given an airing, but so is the mainstream, the down the line Anglican, the charismatic and the evangelical. One runs into Baptist – pastors, former missionaries and Union worthies, Anglo-Catholic Charismatics and Franciscans at Greenbelt. And those who thought they'd travelled too far from Church to ever recognise God again are given hope and reminded of their love for Jesus. In the campsite, in the beer tent and around the food stalls, the talk is almost constantly about God and what he is doing, the shackles of denominational expectation loosened and leaving room to flex the muscles of thought and empathy. People dance together and pray together and sing and worship and listen and talk.

In the space of a day I heard a Muslim and a Jewish man speak in glowing terms of the Jesus I worship, and heard Christians speak with respect and love about and to people of other faiths and marginalised sexualities. I laughed at Christian comics, listened to economics lectures and heard activists from the 'I got arrested for disabling a B52' end of the spectrum to the 'I got a call from Paul Ryan last week' end speak passionately about how Jesus inspires them to change the world.

And the beauty is that if I asked three people what they saw and heard they would have had entirely different experiences. It's always the way. The line-up at Greenbelt is always different, always has something new to catch your eye, be you conservative or liberal, there to be challenged or there to be affirmed. In that way, it is also always the same.

It's a good place, this Greenbelt. A good time. A little glimpse, I always think, of the Body of Christ and the Kingdom of Heaven, where not everything is easy and where we don't all have to be the same, think the same or act in ways that everyone will understand. This year has been no different. Long may it last.

Pic credit: Greenbelt 2013/Jonathon Watkins