Bishop John M. Allin, presiding bishop of the country's Episcopal church, consecrated the bread and wine of the holy communion service yesterday, then held it up for the three men standing at his side--the presiding bishops of three U.S. Lutheran denominations.

As the four men at the altar of the Washington Cathedral consumed the bread and wine, the event became what is viewed as a landmark in the modern movement aimed at bringing about Christian unity and ending centuries of denominational separation.

"An unknown way lies ahead of us," Bishop James R. Crumley, head of the Lutheran Church in America, told the 2,300 Lutherans and Episcopalians gathered in the Episcopal cathedral.

He called the event "a milestone in our religious heritage."

In jointly celebrating the Eucharist the four bishops formally put into effect a statement signed last September permitting members of the four denominations to participate in such ceremonies.

The Eucharist, or communion, is the sacrament or holy ceremony of the Last Supper. Various Christian denominations have varying interpretations of the ceremony, with some accepting its bread and wine through consecration as the actual body and blood of Christ, and others viewing the ceremony as only symbolic of Christ's presence.

Some individual Lutheran and Episcopal congregations and bishops have held joint communion under the principles embodied in the September agreement, but yesterday's service involving the leaders of the denominations was viewed as its formal inauguration.

Besides the celebration of the Eucharist and a sermon by Bishop Crumley the service included a gospel reading by Bishop David Preus of the American Lutheran church and Bishop William Kohn of the American Evangelical Lutheran Church reading prayers of the people. Bishop John T. Walker, Episcopal bishop of Washington and the dean of the cathedral, presided.

The closer association between the Episcopalians and the Lutheran groups, being watched intently in the religious community around the world, appears to suggest at least some movement away from doctrinal exclusivity.

For Episcopalians, the joint celebrations are a step toward recognition of Lutheran clergy who do not claim "apostolic succession," or authority said to date back to Christ's appointment of the 12 apostles.

For Lutherans, who hold strictly to a doctrine of the "real presence" of Christ in a eucharistic service, they appear to mean a greater acceptance of Episcopalians whose interpretation of the Eucharist can vary widely.

In the September statement, each of the denominations said that "the basic teaching" of the other church is "consonant with the gospel" and "sufficiently compatible with the teaching of this church" to have joint eucharistic celebrations.

The 3-million-member Lutheran Church in America, the 2.4-million-member American Lutheran Church and 108,000-member Association of Evangelical Lutheran Churches in America are part of a world body of 70 million Lutherans, one of the largest Christian groupings in the world.

The 2.8-million-member Episcopal Church is part of the 47-million-member Anglican Communion, which through its priesthood is considered a "bridge" between Protestantism and the Roman Catholic and Eastern Orthodox faiths.

Yesterday's service came in the 500th anniversary year of the birth of Martin Luther, the German friar for whom Lutheranism is named.