As three major mainline Protestant denominations prepare to tackle the issue of gays and lesbians in church life at conventions this summer, one of the country's smallest and more evangelical religious bodies--the Mennonites--also finds itself confronting internal dissension over the issue as a historic merger looms next year.

The two major U.S. Mennonite branches, the Mennonite Church and the General Conference Mennonite Church, plan to unite as the Mennonite Church USA next summer in Nashville, Tenn. The combined church would be the largest Mennonite body in the country, with 120,000 members in 1,100 churches.

But before that historic merger can happen, some leaders within the Mennonite Church say the two bodies need to reaffirm the church's position that homosexuality is a sin and marriage is reserved for heterosexuals. Without that guarantee, some bishops say they will not support the integration.

For Mennonites, a small conservative denomination with historic ties to the Amish, the gay issue is acknowledged but rarely talked about. Official church statements in 1986, 1987 and 1995 flatly declared homosexuality a sin, but called on church members to "mutually bear the burden of loving dialogue" on the issue.

Over the past month both sides have raised the rhetoric and brought the issue to the front of the church's consciousness.

In January, 30 bishops in the Lancaster (Pa.) Conference of the Mennonite Church issued a "Statement of Faith and Call to Prayer," calling for a resolution at next summer's convention to clarify the church's stance on homosexuality.

"We believe that we cannot be faithful to our understanding of Scripture that homosexual behavior is sin and join with a church body which does not support those commitments," the statement read.

Last week, opponents fired back with a long-expected advertisement in the Feb. 17 issue of the Mennonite Weekly Review, an independent newspaper serving both bodies. Nearly 700 clergy, academics and others signed the "Welcoming Open Letter on Homosexuality," which called for the church to accept gays and lesbians into church life and "bless monogamous relationships of same-sex couples."

"For us, to take our faith seriously is to tremble when we observe the exclusion by the church of our lesbian and gay sisters and brothers," the ad said.

The internal wrangling in such a small denomination shows the degree to which the homosexual question has become a contentious and nearly all-consuming issue for many of the nation's Protestant denominations.

As much as any issue, homosexuality has divided American Christianity into two distinct camps and galvanized forces on both sides. Talk of schism over the issue has been heard in several mainline Protestant churches.

This summer, Episcopalians, United Methodists and the Presbyterian Church (USA) will take up the issue at their individual conventions.

While Mennonite leaders seem to agree the issue probably won't derail the impending merger, they maintain it may cause some to leave the church.

Jim Schrag, a former general secretary for the General Conference Mennonite Church, is overseeing the merger for both bodies. He said while disagreement is inevitable, he doubts either church would say no to the merger over the issue.

"The communal instinct is very strong among Mennonites, and I think we are sensing more and more that a new church, a new unity, will strengthen our ability to be a solid witness in our society, and for that reason we have every good reason to work out our differences on issues like this," Schrag said.

Those differences of opinion have led to the expulsion of several churches in recent years because of their positions on homosexuality. In 1997, Germantown Mennonite Church in Germantown, Pa.--the country's oldest Mennonite congregation--lost its affiliation in a regional conference because it openly welcomed gays and lesbians into its congregation.

While not always happy with what's being said, some within the church are just happy the issue is finally being discussed.

Anna Dennis, interim executive director of the Minneapolis-based Brethren/Mennonite Council for Lesbian and Gay Concerns, said while the church is not "of one mind" on the issue, an honest discussion will move the church forward.

"The welcoming letter demonstrates that many people care about including all persons in the church regardless of sexual orientation," Dennis said. "(We're) pleased to see Mennonite church members with inclusive stances coming forward to be counted."

For the staff of the Weekly Mennonite Review, the decision to publish the full-page ad was an agonizing one. Editor Paul Schrag, a nephew of the former general secretary, said the newspaper received several dozen letters from church members who either supported or opposed the publication.

In an editorial accompanying the ad, the paper said that by publishing the ad it hoped it would not polarize the church and that it would not comment on the ad's message.

"The effort to achieve unity amid differing convictions is a major theme in Christian and Mennonite history," the editorial said. "The ad is a reminder that it is unrealistic to expect that the new MC/CG union can avoid diversity on some issues."