"We are going to test some advice my father gave me a long time ago," John A. Burgess, the president of the Roscoe Pound-American Trial Lawyers Foundation, told 40 people assembled in a Harvard Law School classroom. "He always told me, 'Don't be a goddam fool, John. Don't discuss religion and politics in public.'"

A wave of nervous laughter swept the room, for the audience Friday morning consisted of politicians, religious leaders, federal and state judges, lawyers and teachers gathered to spend the weekend discussing "Church, State and Elective Politics." Conspicuous among them were leaders of some of the Christian conservative movements, some targets of their past campaigns, and some organizers of groups designed to thwart their growing political influence.

Most of them were meeting for the first time, and the initial encounters were as prickly as might have been predicted. In one of the three panels into which the group divided, former representative Robert F. Drinan of Massachusetts found himself sitting across from the Rev. Robert C. Grant, chairman of Christian Voice Inc.

Drinan demanded to know how Christian Voice had dared to give him, a Jesuit priest, a zero rating on its morality-in-politics scorecard in 1978. Grant said the rating was exactly what a liberal Democrat with Drinan's views on social issues deserved.

In another panel, Robert S. Alley, a University of Richmond professor whose humanist views have been attacked by the Rev. Jerry Falwell on "The Old-Time Gospel Hour," clashed repeatedly with Ronald S. Godwin, vice president of Falwell's Moral Majority Inc. on the links between Falwell's TV evangelism and his political proselytizing.

It was confrontations like this that had made it difficult for the Pound Foundation, which holds an annual conference on a public policy issue, to lure the antagonists to Cambridge. Burgess said that last Thursday "one liberal called and said he would pull out unless we dropped a right-to-life person from the conference and let him bring five of his friends instead. An hour later, the right-to-lifer called and pulled out because we were having the first guy. I told them both to go to hell."

But as the participants worked together in their panels to draft resolutions on a range of church-state questions, the edge of hostility began to wear off. At dinner Friday night, Godwin held forth on Moral Majority's direct-mail fund-raising techniques, much to the fascination of George V. Cunningham and Peter Fenn, directors, respectively, of Americans for Common Sense and Democrats for the '80s, newly formed groups designed to combat the conservative political action committees.

Later in the evening, political feuds were forgotten entirely as former senator Eugene J. McCarthy of Minnesota recited Yeats and Donne to the edification of believers and non-believers alike.

At lunch Saturday, Donna Kuha, who chairs the Massachusetts Women's Political Caucus and is co-ordinator of its recent conference on "the challenge of the New Right," said it had been a mind-changing experience. "I was worried when I came here, by my own anger," she said, "but it didn't come out as much as I expected. The Moral Majority person in my panel [Godwin] was so articulate and so unexpectedly able to laugh at himself that I did not find him threatening. I was impressed with his concern for religious freedom and I didn't see him imposing his views on me."

On the other side, Grant, the director of Christian Voice, said, "I felt an initial freezing sense of hostility from some who had an image of what I was going to be. That hostilty lessened, but I don't think any of us changed our positions on issues. I felt the same thing myself. I have been very critical of the National Council of Churches, and I will be again. But I found myself agreeing with Dean Kelly [the council's executive director for religious and civil liberties] on the First Amendment issues. And he and his wife are lovely people."

But the public, plenary session on Saturday afternoon, when the draft resolutions were debated by the whole group, proved that the issues had not been forgotten -- just set aside.

For three hours, the conferees threaded their way through the church-state thicket in a pattern of shifting alliances. On the first vote, the hard-core strength of the religious right was measured. A resolution opposing use of public school facilities for prayers were passed, 32 to 7, over the opposition of Grant, Godwin and their allies. They gained only four votes as the conference opposed tutition-tax credits for elementary and secondary schools, 28 to 11. But a similar resolution opposing credits for college students passed by a narrow 23 to 18.

When the debate turned to issues of government "intrusion" into religion, the balance of power shifted. By a 27-to-4 margin (with the judges and some others whose organizations have sensitive tax status abstaining), the group condemned the 14-point Internal Revenue Service criteria for determining whether group claiming tax-exempt status is, in fact, a church. By using such standards as an educated clergy and Sunday School classes, the critics said, the government is trying to establish its own definition of religion. By a vote of 22 to 12, they said the burden of proof in such disputes about the legitimacy of a church should be on the government, not the church group. Support for this position from Alley and some of the other liberals made Godwin inquire, laughingly, "What are you guys up to.?"

The consenus held through resolutions opposing state regulation of church schools' curricula and state licensing of their teachers, provided minimum standards of academic achievement in secular subjects are met. They were almost unanimous in condemning state legislation allowing "deprogramming" of people who join religious cults.

But swinging the other way, the group said, by a 29-to-9 margin, that "as a matter of general policy, religious organizations ought to refrain from endorsing specific candidates."

The participants were just about to say their farewells when Alley and Robert G. Begam, a Phoenix attorney, threw a hand grenade into the room in the form of a resolution that opposed (as finally phrased) "efforts to impose on the public school system the teaching of creationism."

Alley said that pressure in many states to gain equal status for the Biblical theory of creation with the theory of evolution amounted to "undermining the teaching of the scientific method." Professor Jude P. Doughterty of the Catholic University philosophy department said, "There is no such thing as the scientific method." The Rev. Thomas Ward, chairman of Massachusetts Moral Majority, said, "To say the Bible is not science is a slap in the face to those of us who believe it is divine revelation."

Gwen Bloomingdale, a Massachusetts Republican feminist, said, "We've been dancing around the real issues for two days here, and now we have to confront one of them. . . . I was trained as a scientist, and I fear for what movements like this [the teaching of creationism] will do to our children."

Alley and Grant, both on their feet, seeking to join the debate, said something to each other, which brought a rebuke from Burgess at the microphone. "Address you comments to the chair," he said. "We're not going to have a brawl here."

The vote was taken, amid general confusion. A count was made but not announced. Both sides were asked to stand again. This time, McCarthy, who have not voted on the first round, stood with the objectors. Burgess, who said he supported the substance of the resolution but objected to its late introduction, said he was also voting no. "The vote is 19-19," he said, "and the resolution therefore fails."

Tom H. Davis of Austin, a former president of the Pound Foundation, said, "Mr. Chairman, I think we have proved the proposition that your father is always right."

But Burgess took another view. Referring to the earlier vote on deprogramming, he said, "I think we should all be proud to have witnessed at least one moment when Bob Drinan and Bob Grant stood together."