PITTSBURGH — A Catholic university has refused to recognize a group for atheist students on campus, but a legal director for the American Civil Liberties Union said that’s OK because the school is private and religious.

Duquesne University senior Nick Shadowen said he believes it’s unfair for the school to not recognize what he calls the Duquesne Secular Society, so about 20 students from his group along with secularists from Carnegie Mellon and the University of Pittsburgh protested Thursday holding signs saying “We don’t bite” and “Support reason.”

“I know Duquesne is a Catholic school,” said Shadowen, a 21-year-old philosophy major from Harrisburg. “I did not think that meant my opinions, my lack of belief in God, would be censored.”

Shadowen said his group should be recognized by the university, which has about 10,000 students in 10 schools of study and recognizes Jewish and Muslim groups whose theological beliefs also are different from those of Catholics.

The rejection means the group can’t meet or advertise on campus and isn’t eligible for school funding.

Student government and university officials defended the move, saying the school welcomes students regardless of belief and doesn’t censor their opinions — but still has the right to not recognize a group whose main purpose is opposing belief in God.

University spokeswoman Bridget Fare said the administration agrees the atheist group should not be recognized.

The ACLU’s legal director in Pennsylvania, Witold “Vic” Walczak, said the private school has a right to not recognize Shadowen’s group. “If this was happening at Pitt, it would be a huge deal,” Walczak said. “At a religious and private university, this is not a constitutional issue.”