Detroit, Mich., Jun 22, 2014 / 06:03 am

The Presbyterian Church (U.S.A.)'s general assembly has voted to allow its ministers to perform "gay marriage" and to redefine marriage as a "commitment between two people," drawing objections that it is moving away from Christian orthodoxy.

"Only declining denominations reject historic Christian standards and in nearly every case that rejection reinforces the decline," Mark Tooley of the Institute on Religion and Democracy said June 19.

"Who respects a church that only echoes the secular world?" asked Tooley, whose inter-denominational organization aims to support orthodox theology and practice in mainline Protestant denominations.

The Presbyterian General Assembly, meeting in Detroit, on Thursday approved an amendment to change the definition of marriage in the denomination's constitution, the Associated Press reports.

The amendment, which passed by a vote of 429-175, defines marriage as "a unique commitment between two people, traditionally a man and a woman."

The amendment must now be approved by a majority of the denomination's 172 regional groups, called presbyteries.

By a vote of 371-238, delegates to the general assembly also voted to allow the denomination's ministers to preside at same-sex "weddings" in states where the civil law recognizes such unions and where local congregation leaders approve.

Bill Norton, a delegate whose Presbytery de Cristo includes parts of Arizona and New Mexico, asked for a delay in any changes.

"We are laying hands on something that is holy, that God has given us, so we need to be sure any changes we make are in accord with God's will revealed in Scripture," he said, according to the Associated Press.

Krystin Granberg, a minister of the New York Presbytery and a supporter of the changes, said she frequently receives requests from friends and parishioners who "want to be married in the church they love and they want me to do it."

The Presbyterian Lay Committee accused the general assembly of making "an express repudiation of the Bible."

The committee in a June 19 statement called for "repentance" and "reform."

Tooley contended that the decisions will hasten the denomination's "already fast-paced demise."

Previous changes within the denomination have eroded its membership, with 428 Presbyterian congregations disaffiliating from the denomination or dissolving since a 2011 vote to eliminate clergy requirements of marital fidelity and chastity in single life.

That vote allowed the ordination of ministers and the selection of lay leaders who are openly homosexual or living in unmarried relationships.

The denomination now has fewer than 1.8 million members, down from 2 million members in 2010, and 3.1 million in 1983, when two Presbyterian denominations merged.