Titan Worldwide

Advertisements proselytizing toothpaste and jeans do not make us question our beliefs. But a series of posters on city buses promoting atheism is intended to do just that.

An Atheist Bus Campaign has arrived in New York. The ads, which say “You don’t have to believe in God to be a moral and ethical person,” underscored by the URL for the New York City Atheists Inc. Web site, will appear on about 20 city buses.

Ken Bronstein, the president of New York City Atheists, a New York affiliate of American Atheists, planned the commercials. He said the posters will only run on Manhattan bus lines, and some members of his organization had already noticed them.

The ads will remain on buses for about a month and will be officially introduced at a news conference on Saturday at Columbus Circle in front of the Time Warner Center at 1 p.m.

“This was a test campaign,” Mr. Bronstein said, adding that he hoped to expand the commercials to the other boroughs in two to three months.

The New York commercials were inspired by the first Atheist Bus Campaign in London last January. They were put on 800 buses in response to a campaign by a Christian group whose relatively innocuous messages contained a URL for a Web site that warned that nonbelievers would “spend all eternity in torment.”

The New York messages are not in response to any such statements, but merely intended to build on what creators believe was the success of the London campaign. Mr. Bronstein said it was something of a challenge to draft a message that the Metropolitan Transportation Authority in New York deemed acceptable.

“I had to be very careful in what they would accept,” Mr. Bronstein said. It took time “to find a statement that we thought was positive, it wasn’t bashing religion and it wasn’t huge.”

Joseph Zwilling, the director of communications for the Archdiocese of New York, said the ads were not offensive in the Catholic Church’s view, given their wording.

“It’s a free country, and they’re allowed to say whatever they want on the side of buses,” Mr. Zwilling said. “They’re not attacking or disparaging the Church as far as I can see.”

Mr. Zwilling said the archdiocese occasionally runs ads in the transit system, usually on the subway. He said the ads “were designed more to invite Catholics back to the practice of their faith.”

The advertisements cost more than $10,000 and were paid for by an anonymous donor.

Jane Everhart, the director of communications for New York City Atheists, said that one goal of the campaign was to increase membership.

Mr. Bronstein said he was more focused on establishing “atheist pride” and promoting acceptance of atheism.

“I’ve had people call me in tears, and tell me they thought they’d never see a sign promoting atheism in New York,” he said.

Mr. Bronstein said he thought American society was opening up to atheism because of a series of events he referred to as an “atheism awakening,” like the publication of best-sellers on atheism by writers like Richard Dawkins and Christopher Hitchens.

But the moment he was certain atheism was acceptable was when he heard President Obama’s inaugural address, which included a reference to “nonbelievers” among an enumeration of various religions.

Ms. Everhart thought it was about time.

“People who are religious have been advertising for generations,” she said. “But atheists never have. We have not come out, and this is part of our coming out.”