Last weekend communist theologian Marika Rose called for the abolition of the police.

It’s nothing remarkable: she has been expressing such views for years. What was different this time is that she was addressing an audience at one of Britain’s largest religious festivals.

Greenbelt is a Christian-based festival of music, comedy, arts, talks, debate, politics, worship and theology. In recent years, it has projected a clearly left-of-centre image.

Taking place every August, it is now held in east Northamptonshire. It attracted over 11,000 punters this year, as numbers rose after falling from the high point of 20,000 some years ago.

Rose’s comments triggered a mixed response. One festival-goer told me she was delighted to hear such radical views at a Christian event. Another wrote: “Shame on you” to Marika.

The controversy provoked a minor Twitter storm, with some apparently angry that such a view should be given a platform at Greenbelt. Nonetheless, I can’t help thinking that there would have been more anger a few years ago.

This is not to say that Greenbelt is centre of communist activism, however its conservative detractors portray it. It has been described as “the Guardian does Jesus.” While this criticism comes from right-wing critics, there is a certain accuracy to it.

Like the Guardian, Greenbelt is liberal and centre-left, preferable to the powerful interests on its right, but broadly accepting of capitalism and compromised by its role as a large commercial institution.

You can hear repeated attacks on poverty and austerity at Greenbelt, but they often focus on specific policies rather than any deeper challenge to class structures.

Thankfully, there are exceptions: this year’s highlights included Teresa Forcades I Vila, often described as “Europe’s most radical nun.”

Pacifist activists Sam Walton and Dan Woodhouse spoke about their attempts to disarm a BAE warplane destined for Saudi use in Yemen. Anglican priest Rachel Mann offered a complex but accessible analysis of the link between militarism and masculinity. Interfaith events looked at how Christians can support struggles against Islamophobia and anti-semitism.

Greenbelt has been a truly liberating event for many people. In the early 2000s, it was the first Christian event at which I saw a same-sex couple holding hands. Nowadays you can see almost as many same-sex couples there as mixed-sex couples.

At most Christian festivals, this would be unthinkable. For countless LGBT+ Christians, Greenbelt was the first place in which they could be open about their sexuality or gender identity.

Socialists at Greenbelt this year welcomed a new tent hosting stalls from co-operative businesses and discussions on the co-operative movement.

There was for the first time a women-focused venue on site: the Red Tent, with a number of events open to all who define themselves as women.

This seems particularly important when transphobia is so prevalent in churches, and when even some on the left wish to deny trans people equality.

There were a number of firmly progressive groups running stalls in the middle of the festival, including the Fellowship of Reconciliation (a radical peace organisation), Church Action on Poverty and groups promoting resistance to the Israeli occupation of Palestine.

In important ways, however, Greenbelt fell short. The theme of this year’s Sunday morning communion service (the main event at Greenbelt) was disability.

There was an inspiring sermon by a disabled teenager as well as contributions from other disabled people about ways in which they are included or excluded.

Remarkably, however, despite all the discussions of poverty at the festival, not a single word was spoken in the service about the way in which disabled people are facing systematic attacks on their livelihoods by a government that is slashing and burning the welfare state.

And over it all hangs the shadow of an incident in 2011, when festival-goer Ceri Owen was dragged from the festival by police as she was sectioned under the Mental Health Act.

The most positive interpretation is that Greenbelt organisers overreacted and misunderstood the situation when they called the police. But far from apologising, they continue to defend their behaviour and Ceri has been banned from Greenbelt ever since.

At the same time, she has become an increasingly prominent mental health activist, frequently appearing in the media to speak about cuts to mental health services.

The importance of Greenbelt for promoting progressive views among Christians should not be underestimated. For some LGBT+ Christians in particular, it has literally changed their lives.

But as Owen’s exclusion demonstrates, when push comes to shove large institutions tend to veer towards self-justification and conventional power dynamics.

Such problems can also be seen in a number of secular left organisations, including certain trade unions. Radical change requires people working at the grassroots from the bottom up.

Thankfully, the more radical punters at Greenbelt will soon be joining in with the large number of protests, vigils and direct actions planned for the run-up to the London arms fair.

Despite Christianity’s many compromises with wealth and privilege, we still have Jesus’s example of standing up to the rich and powerful. The reign of God is not compatible with the power structures of this world.

Symon Hill is a left-wing Christian author and activist. His latest book is The Upside-Down Bible: What Jesus Really Said About Money, Sex and Violence (published by DLT).