It's a particularly remarkable feature of modern British life: the way that in certain circles even the mention of the most modest form of theistic belief is enough to bring down great torrents of hostility. Often the explanation is traceable to the liberal-left's justified concerns about the blurred relationship between religion and state. But, in keeping with the drive of militant secularism to attack the very idea of God as much as what faith means in practice, much of the shouting is usually about philosophical fundamentals. The result: an ongoing scrap between equally staunch believers and non-believers, which arguably gets nobody anywhere.

When we asked our online readers to give us a steer as to the social role played by religion where they lived, it all kicked off again. "I don't trust anyone who needs an instruction manual to tell them how to be good," offered Newbunkie. "My personal view is that all religious groups should be banned," said someone called Youbloodydidwhat.

In response there were slightly more measured claims of religion's practical benefits. "I have seen churches set up hostels for the homeless because the local vicar has encountered so many people sleeping rough in the church porch," wrote JonathanBW. "[They] establish credit unions to help people who are financially excluded … Most of this work does not involve any element of evangelism or proselytising." Similar news came from Manchester, Northampton and Glasgow – and in response, members of the Dawkins-Hitchens tribe dutifully went ape again.

If many of them set foot in Liverpool's Frontline Church, they would presumably explode. It's a standalone evangelical organisation based on the forlorn-looking borders of Picton and Wavertree. Having arrived in Liverpool in 1991, it now draws about 1,000 people – whose average age seems to be around 35 – to the three services staged each Sunday. Recent visitors have included Nick Clegg, Chris Grayling and Cherie Blair; among the first members of the congregation I met the day I visited was a local Labour councillor. Here, God is not acknowledged in that rather bashful way one associates with the tea-and-biscuits model of Anglicanism but loudly saluted. "We are amazed by you," goes one part of the apparently ad hoc liturgy. "We are in awe of you."

Now, I am an unshakeable agnostic. There is something about the unabashed nature of evangelical Christianity that unsettles my very British sensibilities – and I reach my peak of awkwardness during a Sunday service that dispenses with the fusty business of hymns and holy communion, and instead builds itself on music that suggests a grim hybrid of Snow Patrol and LeAnn Rimes. There are collection buckets rather than plates; suggesting that Rymans may have an overlooked sacramental aspect, the flock are invited to write their highest thoughts on Post-It notes, which are then stuck to flip charts.

Drawing on the Book of Joshua, the presiding pastor, a former Bristol GP named Nic Harding, advises his audience to fix their sights on metaphorical mountains, parts of society where their beliefs might be brought to bear. The examples he offers might chill any non-believer to the bone: "Education, healthcare, politics, government – these are all areas where God says, 'Who will claim that mountain?'"

In fact any mention of current affairs brings nonplussed responses from the congregation, and even the pastor tells me that politics is too "top down", and that he wants instead to work against greed and individualism one soul at a time. By way of bowing to the inevitable, I also ask him about the place his church gives to such issues as abortion and gay rights. "To me, those issues are right on the margin of the things we should be focusing on," he says. "The real issues are how we should express and find love for the outcasts and the downtrodden."

This is where he and his people direct their work, as evidenced by Streetwise, a weekly operation in which a handful of volunteers take food, tea and condoms to the city's sex workers. I watch them spend three hours in the encroaching dark as women in various states of drug-related distress flit between their van and streets where money has to be snatched from the jaws of occasionally life-threatening danger. They sometimes quietly pray for those they help, but they don't evangelise. "We're not bible-bashing," one of them tells me. "Whether these girls come to church or not, it makes no difference to how we treat them."

The next day I meet a former sex worker, now apparently off drugs, set on somehow starting college and a regular Frontline worshipper. "I was a prostitute and a drug addict for 11, 12 years – maybe more," she tells me. "God is so forgiving – he wants me to win." Wider society, she says, is "too judgmental … it's: 'That's a prostitute, that's a drug addict.' They don't want to know." And how has the church helped her? "Oh, it saved my life," she shoots back. "I would be dead if it wasn't for this church."

A question soon pops into my head. How does a militant secularist weigh up the choice between a cleaned-up believer and an ungodly crack addict? Back at my hotel I search the atheistic postings on the original Comment is free thread for even the hint of an answer, but I can't find one anywhere.