ST. LOUIS — The United Methodist Church on Tuesday voted to strengthen its ban on gay and lesbian clergy and same-sex marriages, a decision that could split the nation’s second-largest Protestant church.

After three days of intense debate at a conference in St. Louis, the vote by church officials and lay members from around the world doubled down on current church policy, which states that “the practice of homosexuality is incompatible with Christian teaching.” The vote served as a rejection of a push by progressive members and leaders to open the church to lesbian, gay, bisexual and transgender people.

Now, a divide of the United Methodist Church, which has 12 million members worldwide, appears imminent. Some pastors and bishops in the United States are already talking about leaving the denomination and possibly creating a new alliance for gay-friendly churches.

“It is time for another movement,” the Rev. Mike Slaughter, pastor emeritus of Ginghamsburg Church in Ohio, said in a phone interview from the floor of the conference, where he was a delegate. “We don’t even know what that is yet, but it is something new.”

The decision Tuesday is the latest milestone in the fight over the future of American Christianity and over whose views of human sexuality are enshrined as Christian.

Conservatives have left the Episcopal Church over gay rights, Presbyterians have split, and many young evangelicals are leaving their churches over the lack of inclusion of LGBT people.

Meanwhile the nation is becoming increasingly less Christian, and the share of religiously unaffiliated Americans is growing. As mainline denominations that embrace gay rights continue to decline in membership, conservative Christian institutions are growing in power and financial resources.

In recent years, progressive members of the United Methodist Church, including gays and lesbians, have been hopeful about greater inclusion. Six in 10 United Methodists in the United States believe homosexuality should be accepted. Some congregations have celebrated same-sex weddings and had gay, lesbian and transgender pastors, at times receiving church approval to do so even though it technically violated church policy. Punishment of those who violated the rules has been uneven, and church trials for the few who were sanctioned have been unpopular.

Though membership has steadily declined in the United States over the past 25 years — a trend that is true for most mainline Protestant denominations — it has been growing in Africa.

About 30 percent of the church’s members are now from African nations, which typically have conservative Christian views; in many of them, homosexuality is a crime.

Second only to the Southern Baptist Convention in size, the United Methodist Church in the United States has 7 million adherents — including high-profile figures such as Hillary Clinton and Jeff Sessions, the Republican former attorney general.

Methodism has been a major force in American life since before the Revolutionary War, and eventually grew to include a significant African-American membership in the African Methodist Episcopal Church and the African Methodist Episcopal Zion Church.

Methodism in the United States has split about a dozen times in its history, notably over slavery and race. Division over same-sex marriage and LGBT clergy has grown in the church over the past 30 years.

Tuesday’s vote was the latest win for the conservative wing of the denomination. In 2016, the church eliminated a statement in its Book of Resolutions that had supported Roe v. Wade, replacing it with language that called abortion “violent.”

This article originally appeared in The New York Times.