(RNS) -- The nation's two leading Mennonite denominations formally cemented their new relationship as one family on July 5, making the new Mennonite Church USA the largest Mennonite body in the country. Meeting in Nashville, delegates approved the merger of the Mennonite Church and the General Conference Mennonite Church. The merged denomination will have about 125,000 members in 1,100 churches. Although the merger was approved in 1999, differences in governance and membership standards had to be worked out. Church leaders said the new relationship is nothing short of historic. "It's very significant for our two denominations because we've been cooperating for some time, but we've had some significant differences in polity and practice," said the Rev. Ervin Stutzman, the moderator, or president, of the new church. Mennonites are best known for their peace work and commitment to nonviolence. They are theological cousins of the Amish but have a decidedly more integrated lifestyle and do not shun modern life. The practice of "believers," or adult, baptism is also a key tenet. Both the Mennonites and the Amish trace their roots to 16th century Germany and Switzerland, when a band of "radicals," or Anabaptists, largely rejected the Protestant Reformation and were persecuted for their beliefs. Their name comes from an early Dutch leader, Menno Simons. Even though they are more integrated in society than the Amish, Mennonites cling to a simple lifestyle and holy living. Stutzman, however, said his church is entirely mainstream. "The Mennonite Church is a very contemporary church," he said. "These are not people who are living in the past. These are people who look in many ways like people on the street and are dealing with most of the same issues as anyone else in school, work and family." Concentrated in Pennsylvania, Virginia, Ohio and Indiana, the church has a growing ethnic population of Asian and Hispanic members who have changed the racial makeup of the church. Stutzman said at least 20 percent of all board members are non-Caucasian "people of color." One of the largest stumbling blocks toward merger was membership standards -- particularly on the issue of homosexuality. The two churches took different approaches to decision-making, but Stutzman said a middle ground was forged by both sides. The Mennonite Church historically gave local conferences more leeway in determining membership standards, while the General Conference Mennonite Church allowed local congregations more influence. The compromise will give greater authority to local conferences but leave membership standards up to individual congregations, in "consultation" with their conferences. Progressive factions within the church had urged a more welcoming attitude toward gays and lesbians, while conservatives threatened not to join if traditional teachings opposing homosexuality were not upheld. Some liberal-leaning congregations have lost their local conference affiliations because of their openness to gays and lesbians. Under membership guidelines approved Thursday, the church maintains homosexual activity -- along with premarital sex and extramarital affairs -- is "a sin" and marriage is a "covenant between one man and one woman." The church also calls for "dialogue with those who hold differing views." "There may be diversity within the church about how decisions are made or how membership is determined," Stutzman said, conceding that the new rules could lead to a patchwork of different standards within the church.

The denomination will consist of 21 regional conferences, although many are overlapping and nongeographical. The headquarters will continue to be in Newton, Kan., and Elkhart, Ind., with two additional offices to be located in urban areas on the East and West coasts.