The following correction was printed in the Guardian's Corrections and clarifications column, Monday 9 February 2009

The Trinitarian Bible Society, which is running advertisements on buses quoting a line from the Bible, is not a church; it is a Bible publisher. The society has asked us to clarify that its campaign is unconnected to those being mounted by the Russian Orthodox Church and the Christian party.

In the beginning, there was the atheist bus campaign. And it was good. Unless, that is, you were one of the many God-fearing folk who considered it blasphemy. They, however, are planning to get their own back.

A trinity of Christian groups have created their own series of advertisements to run across London buses, the medium of choice for the battle of beliefs, it seems.

The original ads from the British Humanist Association insisted: "There is probably no God. Now stop worrying and enjoy your life."

The new campaign is organsied by the Christian Party, the Trinitarian Bible Society and the Russian Orthodox Church. Their pro-God campaigns will run on 175 buses for two weeks from Monday.

In a somewhat cheeky move, the Rev George Hargreaves of the Christian Party has created a bus advert which proclaims: "There definitely is a God. So join the Christian Party and enjoy your life." It will run on 50 bendy buses in central London, east London and the West End.

Meanwhile, the Russian Orthodox Church has booked 25 supersize bus advertisements, backed by a sponsorship deal with Russian Hour TV, using the line "There IS a God, BELIEVE. Don't worry and enjoy your life."

The Trinitarian Bible Society has taken a less temperate approach, using a line from the bible to scold nonbelievers: "The fool hath said in his heart, there is no God," runs the advertisement's slogan, taken from Psalm 53.1. The church's campaign, which like the others was booked through outdoor advertising company CBS Outdoor, runs on 100 buses.

Last month the Advertising Standards Authority received almost 150 complaints that the atheist bus campaign was offensive to Christians, and that the "no God" claim could not be substantiated.

However the ASA ruled that the campaign did not break the advertising code, concluding that the ads were an "expression of the advertiser's opinion and that the claims in it were not capable of objective substantiation". As such, it said that it was unlikely to mislead or to cause widespread offence.

Writer Ariane Sherine first suggested the campaign in a Guardian Comment Is Free blog last June, to provide a reassuring counter-message to religious slogans threatening non-Christians with hell and damnation. She wrote: "Yesterday I walked to work and saw two London buses with the question: 'When the son of man comes, will he find faith on the earth?' (Luke 18:8) ... If I wanted to run a bus ad saying 'Beware, there is a giant lion from London Zoo on the loose!' I think I might be asked to show my working and back up my claims."