DENVER ? The Catholic Church in Denver, Colorado has barred two children from enrolling in an area Catholic grade school because their parents are lesbians.

The church has actively campaigned against gay marriage, as it teaches that a valid marriage is only between a man and a woman.

"Parents living in open discord with Catholic teaching in areas of faith and morals unfortunately choose by their actions to disqualify their children from enrollment," the Archdiocese of Denver said in a statement.

The Sacred Heart of Jesus School in nearby Boulder, a town known for its liberal politics, informed the lesbian couple of the ruling. The women were told that their children would be able to finish pre-school, but not attend higher classes.

The controversial decision came to light when teachers complained to local media. Protesters showed up at the Sacred Heart Church on Sunday with signs asking "What would Jesus do?"

While some conservative religious groups in the United States have raged against homosexuality, the Catholic Church has been careful not to demonize gays.

"The church does not claim that people with a homosexual orientation are 'bad' or that their children are less loved by God... but what the church does teach is that sexual intimacy by anyone outside marriage is wrong (and) that marriage can only occur between a man and a woman," Archbishop Charles Chaput wrote in a column published Wednesday in the Denver Catholic Register.

Aicila Lewis, executive director of Boulder Pride, a group that advocates for the gay community, said her organization has been hearing from Catholics.

"They want us to be aware that not everyone in the Catholic Church agrees with this decision. It's a wake-up call that this will cause a public outcry and not go unchallenged," Lewis said.

The pastor of Sacred Heart Catholic Church said it would be difficult for a child of gay parents to hear the church's teaching on marriage and then go home and see a different reality.

"We don't want to put any child in that tough position -- nor do we want to put the parents, or the teachers, at odds with the teachings of the Catholic Church," Reverend William Breslin wrote in a blog.