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The Presbyterian Church (U.S.A.) narrowly rejected a proposal to revise the traditional definition of marriage on Friday, a year after it struck down a barrier to ordaining gays.

The Presbyterian General Assembly, meeting in Pittsburgh, voted 338-308 against changing how marriage was defined in the church constitution from a "civil contract between a woman and a man" to a "covenant between two people."

Other mainline Protestant churches have approved gay ordination or permitted individual parishes to celebrate same-sex unions in recent years. The U.S. Episcopal Church, which is holding its national convention through next week in Indianapolis, will consider prayer services for same-sex unions. However, only one major mainline group, the United Church of Christ, has endorsed same-sex marriage outright.

The Presbyterian Church (U.S.A.), like many Protestant groups, has debated for decades whether the Bible prohibits same-sex relationships. The discussion has focused mainly on whether to ordain gays and lesbians who aren't celibate. But as gay acceptance has grown in the broader culture, the church debates have started to include the issue of gay marriage.

Six states and the District of Columbia have legalized gay marriage and three more could do so this year, but 30 states have passed constitutional amendments limiting marriage to unions of a man and a woman. Throughout debate on the measure Friday, Presbyterian clergy from states where gay marriage is legal said they have been inundated with requests to officiate at same-sex weddings and were upset that they had to risk prosecution in church courts to do so.

The highest Presbyterian court found the Rev. Jane Spahr of San Francisco guilty of misconduct in 2010 for officiating at same-sex weddings when they were legal in California. According to the court's rulings, clergy are allowed to bless same-sex unions but not to perform weddings.

In a sign of continuing differences over same-sex relationships, the vice-moderator of the Presbyterian General Assembly resigned Wednesday after controversy over her recent decision to sign a marriage license for a same-sex couple.

Opponents of the new definition of marriage said it would violate the word of God, divide the Presbyterian Church and alienate the denomination from its many partner churches overseas.

In a trend occurring in many denominations, the Presbyterians have been losing members for decades. Last year, the denomination dropped just below 2 million members, and several theologically conservative churches have left to affiliate with like-minded denominations.

Late Thursday, the Presbyterian assembly very narrowly rejected a plan to divest from three companies whose products are used by the Israeli government to maintain the occupation of Palestinian territories. The voters split 333-331, with two abstentions. Instead, Presbyterians adopted a measure calling for investment that contributes to peace in the region.

On Friday morning, pro-Palestinian advocates tried unsuccessfully to revive the divestment proposal. Delegates did, however, approve a boycott of goods produced by settlements in the territories, including Ahava skin care company.