THE young Evangelical Lutheran Church in America further cemented its unity this week, adopting its first statements on social issues since the church's formation in 1988.Delegates to the denomination's 1991 Churchwide Assembly in Orlando, Fla., adopted positions on abortion and the Middle East, among others. The 5.2-million-member denomination was formed from the merger of the American Lutheran Church, the Association of Evangelical Lutheran Churches, and the Lutheran Church in America. It is the largest Lutheran denomination in the United States. On the abortion question, the assembly approved a statement calling abortion "an option only of last resort" acceptable when there is a "clear threat to the physical life of the mother," in circumstances of "extreme fetal abnormality," and in cases of rape or incest. The ELCA delegates rejected a resolution that labeled abortion a sin in all circumstances, one that said life begins at conception, and one calling for respect for women's individual choices regarding abortion. The church's Commission for Church in Society, which developed the statement, said it seeks "to move beyond the stereotypical 'pro-choice' or 'pro-life' positions to establish new common ground of crucial, biblically-rooted values from both perspectives." "The concern for both the life of the woman and the developing life in her womb expresses a common commitment to life," the statement said. Debate over the issue was given added tension when Roman Catholic Cardinal John O'Connor, of New York, in an unprecedented move, wrote to an assembly delegate urging a vote against abortion. The assembly also voted to support United Nations peace efforts in the Middle East and called for an end to further US loan guarantees to Israel unless it stops building settlements in the West Bank. The assembly's actions were significant in helping to move along the unification of the three former denominations into one church. The merger has been hampered by different previous denominational positions on social issues and the ministry, the difficulty of merging bureaucracies, and serious financial problems. Despite these difficulties, the delegates gave a vote of confidence to Bishop Herbert Chilstrom, reelecting him as denominational head for an additional four-year term. The denomination is also wrestling with greater ecumenical questions, such as whether to adopt a recommended mutual recognition agreement between the ELCA and the Episcopal Church in the USA. The Lutherans have put this on hold while sorting out their position on the ministry. The controversial accord calls for the Lutherans to adopt the doctrine that bishops must have an historic succession traceable back to the early church, while Episcopalians would have to recognize current Lutheran bishops, who do n ot claim historical succession. The meeting was the latest involving a large US Protestant denomination this summer. The Episcopal Church's General Convention in July compromised on the issue of whether to ordain homosexual men and women as priests by affirming a traditional definition of marriage, noting that church leaders could not reach a definitive conclusion on the issue, and calling for additional study on the matter and a report to the next convention.