In a novel legal attack on a state’s same-sex marriage ban, a liberal Protestant denomination on Monday filed a lawsuit arguing that North Carolina is unconstitutionally restricting religious freedom by barring clergy members from blessing gay and lesbian couples.

The lawsuit, filed in a Federal District Court by the United Church of Christ, is the first such case brought by a national religious denomination challenging a state’s marriage laws. The denomination, which claims nearly one million members nationwide, has supported same-sex marriage since 2005.

“We didn’t bring this lawsuit to make others conform to our beliefs, but to vindicate the right of all faiths to freely exercise their religious practices,” said Donald C. Clark Jr., general counsel of the United Church of Christ.

The denomination argues that a North Carolina law criminalizing the religious solemnization of weddings without a state-issued marriage license violates the First Amendment. Mr. Clark said that North Carolina allows clergy members to bless same-sex couples married in other states, but otherwise bars them from performing “religious blessings and marriage rites” for same-sex couples, and that “if they perform a religious blessing ceremony of a same-sex couple in their church, they are subject to prosecution and civil judgments.”