The atheist messages came after a £140,000 fundraising drive
Three separate pro-God advert campaigns on the sides of London buses are set to hit city streets.
Buses adorned with the slogan "There definitely is a God" are from the Christian Party, while the Trinitarian Bible Society chose a Biblical verse.
The Russian Orthodox Church is also preparing bus adverts.
The adverts, which are unrelated, come a month after the British Humanist Association placed "no God" slogans on buses across England.
Those adverts, which read: "There's probably no God: now stop worrying and enjoy your life" prompted complaints from the group Christian Voice and from individuals.
The Advertising Standards Authority ruled that they did not breach acceptable standards.
The Christian Party, led by George Hargreaves, raised enough money for their adverts to appear on 50 London bendy buses.
Their full advert reads: "There definitely is a God; so join the Christian Party and enjoy your life."
Mr Hargreaves said the ad campaign is being funded by donations to his party. He is planning to contest June's European Parliamentary elections.
The Trinitarian Bible Society's advert is not a direct response to the atheist campaign, said the group's assistant general secretary, David Larlham.
"While there is an element of being spurred on, this is not to be seen only as a response to the atheists," Mr Larlham said.
He added that the society has regular poster campaigns in train stations promoting Christianity and offering free Bibles.
The group, with a mandate to distribute the Bible internationally, has chosen the message from Psalm 53.1, which reads: "The fool hath said in his heart, There is no God."
The cost for their two-week campaign on 100 buses is £35,000.
The Russian Orthodox Church plans ads on 25 buses that read: "There IS a God, BELIEVE. Don't worry and enjoy your life."