More than 1,400 Washington area Catholics crowded into Gonzaga High School's gymnasium yesterday for a day-long conference on nuclear warfare, the beginning of what church officials plan as an intensive grassroots education and action program on an issue that has become a central concern in American Catholicism.

The church, Archbishop James A. Hickey told yesterday's gathering, "will not permit the moral and human dimensions of nuclear policy to be neglected or ignored in the deliberations of experts and politicians.

"The decisions about the American nuclear arsenal are among the most important moral dilemmas of American citizenship. They cannot be left to just the technicians or a few leaders."

Yesterday's speakers from government, the academic community and antinuclear organizations as well as the church were deliberately chosen to reflect diverse points of view, Hickey said. There was no attempt made to adopt resolutions or reach a consensus.

"We must enter this debate with the proper attitude," said the Rev. Brian Hehir, international affairs adviser for the National Conference of Catholic Bishops. "It's a very complicated issue and simplistic answers will not lead to understanding or insight."

Hehir called the growing involvement of U.S. Catholic leaders in the nuclear warfare issue "the most significant development in the American church" in the last few years.

Yesterday's turnout was nearly double what church leaders expected. Participants were about evenly divided between men and women and included a wide age range.

Although there were a few peace activists on hand, John Carr of the archbishops staff characterized the large majority as "people who have never marched in a protest. They aren't activists," he said. "Activists wouldn't sit still so long."

Nationally, a committee of the hierarchy has been at work for more than a year on a definitive statement on the morality of nuclear warfare.

Of the nation's 280 Catholic bishops, 85 have issued individual statements on the issue, and 135 have endorsed a bilateral nuclear freeze.

Last June, Hickey issued a 3,000-word pastoral letter in which he called for a bilateral freeze on nuclear weapons. The statement also launched the archdiocese-wide "Call to Peacemaking," of which yesterday's conference was the kick-off.

Next month, leaders will be trained to conduct peacemaking conferences in their parishes.