On his business card, atheist talk show host Dennis Horvitz calls himself “The David Letterman of the Hopelessly Damned.”

Mr. Horvitz, 57, is the bespectacled co-anchor of “This Week in Atheism,” a “McLaughlin Group”- style chat show that tackles issues of church-state separation. He also hosts “New York City Atheists Live (On Tape),” an interview show whose recent guests have included an evolutionary biologist and a Scientologist-turned-atheist. The half-hour public access shows, and another called “The Atheist Book Club,” are productions of New York City Atheists and their Center for Atheism.

Taped in the Upper East Side living room of the group’s president, Kenneth Bronstein, the broadcasts are part of the atheist group’s growing outreach. The makeshift studio is decorated with halogen lamps, FDNY memorabilia, and an aquarium built into the wall.

The group has plans to add new television shows on the Manhattan Neighborhood Network each year, with the goal of producing enough programming to support a broadcast network. While local atheists used to set up booths at Manhattan street fairs, about three years ago they moved to the Time Warner Center at Columbus Circle, where they don’t have to pay a fee.

From March to October, the group sets up a white-tented booth with eye-catching banners declaring “Total Separation of Church and State” and “Join NYC — Atheists.” Volunteers hand out copies of their newsletters and invite passers-by to sign up for their mailing list, which now has more than 1,000 names. Occasionally, those on their way in or out of the nearby shopping mall will leave a small donation on the table.

Messrs. Bronstein and Horvitz — who both grew up Jewish — avoid words like “preaching,” “converting,” and “evangelizing” when discussing their community outreach. Yet they acknowledge that the group is stepping up its efforts to bring more atheists “out of the closet” in New York City.

NYC Atheists has more than 100 members of all ages and religious upbringings. Membership, Mr. Horvitz said, would be much higher were atheism not so taboo in America. “A lot of people are afraid to come out as an atheist, or they don’t have a place to come out in,” he said.

The group holds Sunday lunch meetings and lectures about once a month. Members speak with fervor about influence of the so-called religious right and what they see as their own marginal status in America.

At 13, around the time of his bar mitzvah, Mr. Bronstein, who grew up in Boston, renounced his faith in God. “I decided that I would own my own life,” Mr. Bronstein wrote of his decision in a “sermon” published in NYC Atheists newsletter this month. “What I meant by that is: I would be my own master, not controlled by any mystical or supernatural force. I would use reason and faith to guide my life.”

Mr. Horvitz, a native of New Bedford, Mass., said he has been a nonbeliever his entire adult life. Only in recent years, sensing the growing political power of the religious right, did he become an “atheist activist,” he said.

Some faithful, however, see atheist outreach tactics as a form of spreading the “gospel” of their un-church. “They do it with a religion-like sense of urgency to ‘convert’ people to their position,” a Catholic priest and the editor of the religion journal First Things, Father Richard John Neuhaus, said. “In many cases, they do believe that if they could convince 99.9% of the world to reject religion that we’d all live together in peace.”

He added: “On one level, it’s an honest disagreement; on another, there’s this compulsive need to rage against something that is as common to the human condition as breathing and eating — believing that you are part of the universe and, more importantly, believing that you’re not God.”

Recent polls have shown that about nine out of 10 Americans believe God exists or probably exists — though far fewer than 10% label themselves as atheists. Many nonbelievers prefer terms like secularist and humanist, partly because of the taboo associated with the atheist moniker.

Members of NYC Atheists say they’re determined to erase the stigma that atheists are necessarily immoral — even unpatriotic.

Their cause has been buoyed by the success in 2006 of three books by authors who argue that religion can have a negative impact on government and society: “The God Delusion” (Houghton Mifflin), by Oxford University biologist Richard Dawkins; “Letter to a Christian Nation” (Alfred A. Knopf ), by a doctoral candidate studying neuroscience, Sam Harris; and “Breaking the Spell” (Viking), by a Tufts University philosophy professor, Daniel Dennett.

The ideas presented in the three books are sometimes deemed “The New Atheism” because of their support of aggressive outreach to encourage like-minded nonbelievers, or “freethinkers,” to join their battle.

“I like to use the term consciousness raising — that’s what we’re trying to do,” Mr. Dawkins said in a phone interview from his office in Britain.

He said as the religious right has become more politically influential, the atheists have been forced to become more vocal.

A New York-based editor of an atheist news and opinion journal called the Focus, Suzy Lanza, said atheist groups are not looking to convert believers to nonbelievers, but to show unaffiliated atheists and those who question their faith traditions that an intellectual — and social — community exists for them. Said Ms. Lanza: “I think it’s good that atheists do not continue to be the unmentionable, even if there is a great deal of opposition to our views.”