A priest at St. John's University said he was resigning his leadership position because of the Vatican's latest statement that homosexuals should be barred from entering the Roman Catholic priesthood.

"Because I can no longer honestly represent, explain and defend the church's teaching on homosexuality, I feel I must resign," the Rev. Bob Pierson said in an e-mail Wednesday to administrators and students at St. John's and the nearby College of St. Benedict.

The Vatican announced last month that it was toughening its stand against gay candidates for the priesthood, advising that men with "deep-seated" gay tendencies or who "support so-called gay culture" shouldn't be admitted to seminary or ordained. Others with "transitory" homosexual inclinations can be accepted if they have "clearly overcome" them for three years.

Several gay priests are now questioning whether they can continue serving the church. The Rev. Leonard Walker quit his parish assignment in Mesa, Ariz., in protest. The Rev. Thomas J. O'Brien, a Jesuit retreat director from Bloomfield Hills, Mich., disclosed his sexual orientation publicly — a rare step among clergy — saying the Vatican document promotes "bigotry."

Pierson, the chaplain and director of campus ministry, said in the e-mail that that he is gay and celibate. He said he did not accept several elements in the Vatican document, including the assertion that homosexuals are "objectively disordered."

"I am not an infallible person, but I cannot remain silent about my disagreement in conscience with this document, or the church's teaching on homosexuality," said the priest.

Pierson said he would resign effective Jan. 15. He will remain a member of the monastic community at St. John's Abbey, which is on the campus but technically separate from the university.

University spokesman Michael Hemmesch said the school regretted Pierson's decision but "we must respect his personal conscience."

Pierson did not immediately return a message left at the university Thursday.