Media playback is unsupported on your device Media caption Watch: Inside a meeting of The Sunday Assembly

St John the Evangelist in Leeds can rarely have hosted such an ungodly meeting.

The Sunday Assembly - dedicated to providing "the best of church but without God" - was on the latest stop of its UK tour.

Spilling out through the open door of the 400-year-old church came voices united in a rendering of Queen's Don't Stop Me Now.

Inside, a couple of hundred people - average age about 35 - clapped rhythmically, swaying in the venerable pews.

But for the choice of music it was just like a certain sort of church.

'Jesus jokes'

There was an overhead projector, a small team to lead the singing and a charismatic figure using his rangy body to urge on the congregation.

He is one of two stand-up comedians who co-founded the Sunday Assembly - Sanderson Jones.

Compared to the big zero that awaits, a cup of coffee can be transcendental, the touch of a lover's hand can be mystical Sanderson Jones, Co-founder of the Sunday Assembly

During the evening I asked him whether having this long-haired, bearded figure at the front, calling on people to follow him reminded audiences of anyone.

"I had long hair and a beard long before starting the Sunday Assembly," said Mr Jones. "But it does mean that Jesus jokes do get made."

There is something vaguely messianic about Sanderson Jones and his humanist project.

He talks about its mission statement - to live better, help often and wonder more - with proselytising zeal.

He wants to raise half a million pounds to spread the word throughout the world, starting hundreds, or even thousands, of assemblies.

"We come from nothing and we go to nothing," he insists. "Compared to the big zero that awaits, a cup of coffee can be transcendental, the touch of a lover's hand can be mystical. If you don't believe in God that just makes life even more precious."

The inherent preciousness of life, and the human capacity to do and experience good without contact with the divine, breathe through the programme.

Image caption There are few differences with an actual church service

The event is a brazen copy of a church service.

As well as emotional and uplifting songs, there was a talk from a woman who had turned her life around by volunteering, another from a scientist about the human propensity to misperceive reality and a minute's silent reflection.

During a rendering of Dire Straits' Walk Of Life a collection was taken.

"We both wanted to do something like church but without God and we just nicked the order of service," admits Mr Jones.

"People want to think about improving themselves and helping other people and doing all of that in a community where you forge strong relationships. I mean what a package. Why on earth wouldn't you nick it?"

The project is designed to appeal not just to atheists but also to agnostics, or the "spiritual seekers" that churches may find difficult to hold on to.

I think doctrine does develop - it wasn't born in Palestine 2,000 years ago Canon Adrian Alker

One of the organisers, Andy Nightingale, belongs to what he said was a conservative Baptist church in Leeds.

He said fellow Baptists would understand his active role in the Sunday Assembly and had been happy to lend their overhead projector.

"They wouldn't be surprised," said Mr Nightingale. "The Sunday Assembly doesn't dismiss the church, it welcomes people from all faiths.

"It's really important to spend time understanding people who have different views."

Sitting discreetly near the back was the only person present wearing a clerical collar.

Canon Adrian Alker's job is to attract people like Andy to the Church of England by fostering imaginative new ways for it to practise and explain Anglican Christianity.

He accepted that many in the Church's target audience have become disenchanted with what they perceive to be compulsory but dubious doctrines - such as a belief in the birth of Jesus to a virgin and that Jesus was physically resurrected from the dead.

Canon Alker said the answer was not for the Church to place less emphasis on God, but actually to make more effort to explain a more nuanced idea of what God was.

"I think doctrine does develop," he said. "It wasn't born in Palestine 2,000 years ago. I think there should be open discussion, and [there] often is, about these core elements of the Christian faith."

'Sanderson effect'

After a final song, nearly everyone stayed for superior tea and cake, served at the back of the church.

The verdict was overwhelmingly positive.

"I didn't know what to expect," said one 20-something woman, "but it's something I've been looking for for a while. So I think I'll be coming again."

"I've said it before, that I wish there was a church I could go to, but I don't believe in God," said another. "Because they used humour I think that made it really accessible."

The Sunday Assembly - a brand its creators are determined to protect - is to continue meeting in Leeds, although I could not help feeling they would miss the "Sanderson effect" - the warm energy emanating from the front of the church.

For Sanderson Jones himself, the end of his UK tour signals the start of a more ambitious overseas project starting in the US.

At the very moment public trust in religious institutions is wavering, this irreligious movement is building an institution of its own.