BALTIMORE (AP) _ Presbyterians from around the country lined up today to speak against a church report challenging traditional notions of Christian sexuality.

Forty-three presbyteries, each representing groups of congregations, have joined in opposition to the report. Each reserved the right to speak for up to three minutes during a public hearing that began this morning at the 203rd General Assembly of the Presbyterian Church (U.S.A.).

''The report fails to accept biblical teaching on human sexuality, that is, heterosexual marriage,'' said church member Gary Tate of Seattle, Wash.

Caroline Gourley of Morganton, N.C., said, ''The report not only justified, but advocated behavior that we felt against scripture. The report defines norms of culture rather than the church interpreting what culture should be.''

Those in favor of the report were expected to speak later today.

About 6,000 church members are in Baltimore for the general assembly, which opened Tuesday and will continue through June 12.

The 200-page report, prepared by a task force of church leaders and theologians, has caused a furor within the church, selling more than 27,000 copies.

''Keeping Body and Soul Together: Sexuality, Spirituality and Social Justice,'' argues that premarital sex, homosexuality and bisexuality should be accepted by the church if they are engaged in by genuinely consenting adults.

''The moral norm for Christians ought not be marriage, but rather justice- love,'' the report says, defining ''justice-love'' as ''right-relatedness with self and others.''

Gordon Stewart of Cincinnati is chairman of the committee hearing today's emotional debate.

He said the committee, whose members were selected randomly by computer from commissioners representing local presbyteries, will listen to all points of view and then issue a recommendation to the General Assembly on Monday.

''We are free to respond as the committee feels to be wisest for the church, including complete approval or complete rejection,'' he said. ''It's a big task and an opportunity for the church, which is waiting for the general assembly to speak,'' he said Wednesday.

On Wednesday, the Southern Baptist Convention meeting in Atlanta approved a resolution upholding the traditional Christian standard that sex should be reserved for marriage - a message many believe was aimed at the Presbyterians.

The resolution urged ''all Christians to uphold the biblical standard of human sexuality against all onslaughts.''

Stewart declined to comment on the Baptists' resolution.