Los Angeles — From numerous pulpits across America, peace is being preached - and peacemaking demanded - with unprecedented fervor.
Theologians and church officials note the number of so-called mainstream churches that have stepped forcefully into the nation's debate on the nuclear freeze and nuclear disarmament issues - carving out a philosophy that one Lutheran official calls ''nuclear pacifism.''
Nor have these churches stopped at simply speaking out against nuclear weapons. Many denominations have officially placed peace at the top of their agendas and have created peace-education programs.
Already many local churches have spoken out on the freeze and disarmament issues. In California, for example, a number of Los Angeles churches have been involved in three ''peace'' or ''freeze'' sabbaths, days of worship during which congregations concentrate specifically on peace and nuclear war. In addition, in communities like Northfield, Minn., local ministers have invited freeze proponents to speak to their congregations as part of social issues forums.
''The strength of declarations made by the mainstream churches is really, as far as I know, unprecedented,'' says Dr. Harvey Cox, a widely respected theologian at the Harvard Divinity School who has been active in the nuclear freeze movement.
Historic peace churches - such as the Mennonites and Quakers - have long been involved in peace issues. Mainstream churches, too, have entered the debate at various times, perhaps most notably, in recent years, during the war in Vietnam.
However, it has only been in the past year or two, as the public's concern over nuclear war has mounted, that the issue has become a focus of attention for religious bodies, cutting across denominational lines. The churches' emphasis on the issue is expected to have political implications as well, as their discussions broaden the audience for nuclear-freeze activists.
Observers say the impact of church involvement in the nuclear debate won't really be felt until it translates into votes at the ballot box. An early test of that will come this fall, as voters in several states weigh the merits of a nuclear freeze. In at least one state, California, churches are playing what freeze-measure coordinator Harold Willens calls a ''very important'' role.
Among various elements in the current theological debate:
* Roman Catholic bishops are preparing to issue a major statement, in the form of a pastoral letter, providing guidance for their followers on issues of peace and war. Although church officials will not disclose the contents of the 70-page document, which will be discussed at a November conference of the bishops, theologians are expecting the letter to have a profound impact.
According to Dr. Cox, a Protestant who has addressed many church leaders on nuclear issues, the statement will ''create an important crisis of conscience'' for Catholics in the military service who are involved with nuclear weapons.
Father Brian Hehir with the US Catholic Conference says ''crisis of conscience'' is too strong a phrase, but he adds that the statement is meant to guarantee an examination of conscience among Catholics - not just in the military service, but throughout the denomination.
Already, 85 of the 300 Catholic bishops in the US have spoken out against nuclear weapons. Among those bishops is Seattle's Archbishop Raymond Hunthausen, who has told his followers, '' . . . our security lies not in demonic weapons which threaten all life on earth. Our security is in a living, caring God.''
* At its biennial convention held in early September, the American Lutheran Church - representing approximately one third of the country's Lutherans - voted overwhelmingly to commit itself to the ''elimination of nuclear weapons on earth.''
In addition to endorsing the freeze as a first step in that direction, the convention, made up equally of laity and clergy, called for the US to take preliminary unilateral steps towards reversing the arms race. The convention also made ''peacemaking'' a churchwide priority, establishing activities that include the development of curriculum for children.
''This is a breakthough for us,'' says Charles P. Lutz, director of the ALC's Office of Church in Society. ''This is the first time our church, which is conservative politically and theologically, has taken this stand.''
* The Episcopal Church, at its recent triennial convention, passed a broad peace and reconciliation effort, which included an endorsement of the freeze and a call for a no-first-strike pledge by the US.
In addition, its House of Bishops issued a pastoral letter calling the nuclear arms race ''the most compelling issue in the world public order.''
''This is really the first time the Episcopal Church has addressed the whole issue,'' explains the church's public issues officer, the Rev. Charles Cesaretti , who notes that the peace resolutions were initiated at the grass-roots level.
Although there are some fundamentalists who see a nuclear holocaust as an inevitable and apocalyptic event, it does not appear that smaller, conservative denominations are organizing against the nuclear freeze. The Moral Majority, which draws its support largely from conservative Christians, says it is not planning organized opposition in the form of group demonstrations. But it is now in the midst of researching, developing, and raising funds for an anti-freeze campaign, according to Dr. Rod Godwin, vice-president and chief operating officer of the organization.