SAN FRANCISCO—Conservative Christian activists, conservative evangelicals and Roman Catholics have joined forces in fighting same-sex weddings in San Francisco, according to the San Francisco Chronicle.

Christian faith appears to be the main reason people oppose gay marriage. Public opinion polls show a direct link between how often Americans go to church and how likely they are to oppose homosexual marriage. A Gallup Poll showed 63 percent of weekly church attenders favored a Federal Marriage Amendment, while only 42 percent of those who seldom or never attend church backed the proposal.

A poll conducted by the Pew Forum on Religion and Public Life suggest that opposition to same-sex marriage is widespread among white evangelical Protestants (84 percent) and blacks (65 percent). Other mainline Protestant Christians showed a 20-point drop in opposition to same-sex marriage (from 64 percent to 44) and a 19-point drop among white Roman Catholics (from 60 percent to 41 percent) but only a 1-point decline among white evangelical Christians and African Americans.

The California Supreme Court last week temporarily halted gays and lesbians from obtaining marriage licenses at San Francisco City Hall pending a full hearing in late May or early June. But religious conservatives are prepared for a long fight.

“This is just one battlefield of a war,” said Benjamin Bull, the church counsel of the Alliance Defense Fund. “This is a struggle between the Judeo-Christian view of marriage and a relatively small population group that is clamoring to redefine the majority's view of marriage.”

Some of the nation's largest churches are on Bull's side.

The nation's three largest Christian denominations – the Roman Catholic Church, the Southern Baptist Convention and the UnitedMethodistChurch – all stand opposed to gay marriage. That opposition was challenged by a court decision permitting same-sex marriage in Massachusetts, and by San Francisco Mayor Gavin Newsom's defiance of California marriage laws.

United States Conference of Catholic Bishops this month reaffirmed its support for amending the U.S. Constitution to define marriage as “only the union of a man and a woman.”

Most conservative Protestants, especially Southern Baptists and other evangelicals, agree with the Catholic bishops about same-sex marriage. Richard Land, president of the Southern Baptist Ethics and Religious Commission, said a constitutional amendment was “the only way to adequately deal with this judicial assault on the sanctity of marriage being defined as God intended it.”

Most of the nation's mainline Protestant churches also oppose same-sex marriage. The bylaws of the UnitedMethodistChurch describe gay sex as “incompatible with Christian teaching.”

While most Christians agree church leaders differ over the necessity of a federal amendment. The Rev. Harold Mayberry, pastor of the FirstAfricanMethodistChurch in Oakland, Calif., has preached against homosexuality to his congregation of 2,800, but opposes a constitutional amendment.

“I'm comfortable in what I believe in,” Mayberry said, “I'm not rejecting people. As God loves, we love. I don't reject thieves, I reject thievery.”