A resurgence of concern for visible church unity is marking the sixth assembly here of the World Council of Churches, which represents 400 million of the world's Christians.

It is reflected in the largely favorable reactions being expressed to a doctrinal agreement reached last year in Lima, Peru, by theologians from the world's major Christian traditions who met under WCC auspices. The Lima Agreement, as it is known, found "doctrinal convergences" in three basic elements of the Christian faith that have often divided the churches: baptism, the eucharist and the ministry.

The scholars who participated at Lima represented not only the Protestant and Orthodox denominations that make up the WCC, but also such nonmember churches as the Roman Catholic Church, the Southern Baptist Convention and the Lutheran Church-Missouri Synod, which are represented on the WCC's Faith and Order Commission.

A eucharistic liturgy incorporating the Lima document convergences was celebrated Sunday in a large tent on the grounds of the University of British Columbia, where the WCC is holding its 18-day assembly. About 3,500 of the assembly participants attended.

Dr. Robert Runcie, the archbishop of Canterbury (Anglican), who was chief celebrant, said, "This service points to our future unity," although he noted it was an occasion for both joy and pain since representatives of some churches could not take communion for reasons of conscience.

He was referring to Roman Catholics and Orthodox members who, according to rules of their churches, can receive communion only when it is consecrated by their own priests. However, some Catholic and Orthodox representatives did participate in the service as readers and prayer leaders.

The dilemma Christians have concerning the eucharist was pointed up by Dr. William Lazareth, retiring executive of the Faith and Order Commission, who said they "agree on the makeup of the eucharistic meal but not on the propriety of the waiters who serve it."

The WCC-member churches and others that participate in the Faith and Order Commission are being asked to give their responses to the Lima document, including "the extent to which your church can recognize in this text the faith of the church through the ages." The official responses are due by the end of 1984.

This process of reception and response is intended to be a major step toward a fully mutual recognition of baptism, eucharist and ministry, according to the commission's vice moderator, Dr. John Deschner, professor at Perkins School of Theology at Southern Methodist University in Dallas. In order to achieve visible unity, the churches also will be asked later to agree on a common understanding of the apostolic faith and on common ways of teaching and decision-making.

"In my opinion, this growing strategic clarity about advancing towards visible church unity is the most important development in the World Council since it was formed at Amsterdam in 1948," Deschner told an assembly group here studying unity.

Two of the 20 official delegate-observers from the Roman Catholic Church at the assembly promised that the baptism-eucharist-ministry document will receive consideration from their communion. It is being sent to conferences of Catholic bishops around the world as well as to Catholic seminaries.

The Rev. John Hotchkin, ecumenical officer of the National Conference of Catholic Bishops of the United States, said he believes response to the document from the Catholic Church will be "very positive, with questions about certain areas needing further study."

"If the world's churches see the document as acceptable, it will provide a new floor on which the ecumenical movement can build," Hotchkin said. "Then we can assume agreement on the central Christian realities and can go on to tackle remaining important questions such as authority in the church."

Lazareth, a Lutheran theologian soon to become pastor of a New York City church, said the eventual goal of the unity efforts is an ecumenical council that would be recognized by all of Christendom. The 1,200th anniversary of the last such council, held in A.D. 787, may be observed in 1987 with a major faith and order conference that would seek further advances toward church unity, Lazareth said.

The WCC assembly here is expected to authorize the holding of such a conference.

The role of the WCC, Deschner said in his report as vice moderator of the Faith and Order Commission, "is clearly not to dominate or even guide steps toward unity which only the churches themselves have authority to discern and take." Its role, he explained, "is rather to serve them in their hope for advances."

He said the Vancouver assembly should develop some recommendations to the churches about how to participate in the "process of reception" of the baptism-eucharist-ministry document.

In his report, Deschner also discussed recent emphases of the movement for church unity. He cited increased "informal ecumenical activity," "powerful pressures for widened participation of laity, women, minorities and youth," and "an expansion of the ecumenical agenda."

"Widened participation brings new demands for relevance, and new perceptions of 'secular' issues for which church unity is somehow felt to be the key," he said. "Pressures for new kinds of ecumenical thinking grows."

Not all the unity developments involve the WCC or other ecumenical agencies, Deschner pointed out. He said there were at least 19 bilateral conversations taking place between various communions on the international level, plus scores of national and regional ones. The Roman Catholic church is participating in eight and the Orthodox in several, he said.

Deschner also reported that at present there are 13 continuing transconfessional neogiations looking toward union being conducted by 60 churches in 12 counties. There now exist some 30 transconfessional unions--more than 60 if one includes the intraconfessional, he said.

The interest of Roman Catholics in the World Council has been shown not only by the presence of 20 official delegated observers to the assembly here, but by participation of more than 100 other Catholics as advisers, staff and visitors.

Pope John Paul II sent a greeting assuring the assembly participants of "my deep pastoral interest and closeness to Canada."

This assembly also has been marked by increased participation of representatives of Judaism, Hinduism, Buddhism and Islam both in plenaries and in programs for visitors.

Rabbi Marc H. Tanenbaum, interreligious affairs director of the American Jewish Committee, who participated in a session on an assembly subtheme, "Life, a Gift of God," said, "The central moral and human crisis of our time is the dignity of human life, which is being battered on every continent on earth.

"What unites Jews and Christians, as well as Moslems and others, what binds them more powerfully than anything that separates them, is their conviction that every human life is precious in the eyes of God. None is expendable."

At another session, a Sikh poet and philosopher from India, Dr. Gopal Singh, appealed to the Christian delegates to understand the spiritual viewpoints of other faiths.

Meanwhile, the assembly nominating committee has been busy trying to select nominees for the 145-member Central Committee, which governs the WCC between assemblies, now being held every eight years.

The slate proposed for the WCC Presidium, expected to be elected, has been carefully balanced by sex, race, confession and geographical region, as has the Central Committee slate.

Lois Wilson of Kingston, Ontario, former moderator of the United Church of Canada, is the only North American being nominated for the Presidium. She is scheduled to be one of three women on it, the largest number of women yet.