The president of the largest Christian denomination to endorse gay marriage will officially welcome a Dallas gay megachurch as a member Sunday.

The Rev. John H. Thomas of the United Church of Christ will be the first leader of a mainline denomination to address a predominantly lesbian, gay, bisexual and transgender congregation when he preaches at the Cathedral of Hope, said The Rev. Jo Hudson, the cathedral's rector and senior pastor.

The cathedral, which claims 4,300 members and will be the fourth-largest in the UCC, decided to join last year after the denomination endorsed gay marriage in 2005. Thomas will preach at two morning services, and there will be a special service of induction in the afternoon.

"We believe the Cathedral of Hope's acceptance into the United Church of Christ and Rev. Thomas' visit are important steps in the ongoing journey to the full acceptance of LGBT people with the church and society as a whole," Hudson said.

The Dallas cathedral bills itself as "the world's largest liberal Christian church with a primary outreach to lesbian, gay, bisexual and transgender people."

The Cleveland, Ohio-based UCC, formed in 1957 by the union of the Congregational Christian Churches in America and the Evangelical and Reformed Church, has 1.3 million members. The UCC has a tradition of support for gays and lesbians. It is distinct from the more conservative Churches of Christ, which has some 2 million members in the United States.

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