Washington's First Baptist Church - whose most famous member is President Carter - begins a two-day peace convocation today.

The gathering, bringing together such disparate spokesmen as the Rev. William Sloane Coffin, the antiwar activist, and Southern Baptist preachers, is part of what some national church leaders believe is a new broad-based religious peace and movement in this country.

Many of these new church peace efforts have grown out of the anti-Vietnam War network once led by people such as Coffin. The new church efforts are an attempt to "get the peace movement off the streets and into the churches," he said.

Support, moreover, is coming from church groups never identified with the peace movement, including Southern Baptists, other sectors of evangelical Protestantism, and conventional Roman Catholics who a decade ago deplored the activities of the Berrigan brothers.

Examples of the new religious fevor to fight the arms race and nuclear weapons include:

A day-long Memorial Day service last week during which thousands of Christians in more than 50 cities called for an end of the nuclear arms race. The vigil was sponsored by the Sojourners Fellowship, a Washington based organization dedicated to living in accord with the New Testament.

In February, about 400 Southern Baptists gathered for a weekend convocation in Louisville on the "Peace making Agenda." It was the first conference specifically devoted to peace ever held under the auspices of the Southern Baptists, who tend to the identified more with personal pietism and evangelism than consideration of social and political questions.

In March, a delegation from the National Council of Churches met in Geneva with leaders of the Russian Orthodox Church to explore a mutual concern for peace. Their statement urged the "earliest possible approval" of SALT II accords as a next step toward "real, complete, general and total disarmament."

The Roman Catholic Archdiocese of Hartford, Conn., hardly a hotbed of radicalism, recently issued, as part of the resource material in use by about 130 study and discussion groups in the archdiocese, a 65-page booklet titled, "A Call to Faithfulness: The Arms Race and the Gospel of St. Mark."

In addition to a theological exploration of the topic, the booklet points out that 27.7 percent of Connecticut's workers are involved in military-oriented industry, producing everthing from nuclear submarines to small arms. The booklet also includes suggestions on how to work for peace, and lists secular and church-related peace organizations.

The most eleborate of the church based peace efforts under way is the disarmament program of Riverside Church in New York City, where Coffin is senior minister.

Riverdale's disarmament program, directed by another peace activist of the Vietnam War days, Cora Weiss, held a massive national "Reverse the Arms Race" convocation last December. It also has organized demonstrations against the launching of the Trident submarine, mobilized a Peace Sunday/Peace Sabbath effort earlier this year, and in general continues to hammer away in an effort to roll back the arms race.

The peace convocation at First Baptist Church here this weekend is one of about 70 similar gatherings around the country encouraged by the New York church.

The new efforts for peace are taking different approaches. Some, like the Riverside program, tend to hit hard on the guns-or-butter argument, with ready statistics on how many health clinics could be built for the price of one nuclear submarine. Such arguments also usually contend that nuclear weapons make for a more dangerous rather than a more secure world.

Groups such as the Sojourners come at the problem from a more explicitly religious approach.

"I think the significant thing is that there is a new constituency of people who are involved in this question on the basis of their personal faith . . . because of what they believe about Jesus Christ," explained Wes Michaelson of Sojourners, one of the coordinators of the Memorial Day prayer vigils.

"The people who came [to the prayer vigils] were there not for the eral political reasons or for a rationalist war-is-bad, peace-is-good philosophy, but because of what they believe, because their own personal faith cannot countenance our nation's nuclear policy," he said.

For that reason, he said, groups such as Sojourners continue to stress prayer, worship and "getting people deeper in touch with their own faith and beliefs . . . I believe they need to look at the nuclear issue in light of their stated conviction that Jesus is Lord."

For Christians, Michaelson continued, "there is no way in which our nuclear policy can be called anything but idolatry of the nation....

"We have to get people to raise the basic question, such as 'How can we in Christian terms ever justify the use of nuclear weapons?'"

Michaelson, a former legislative aide to Sen. Mark Hatfield (R-Ore.) does not dismiss the political dimension.

"Ultimately, it does have to be translated into political terms," he said, adding that he believes "the nuclear issue will be a major issue in the 1980 elections."

While there are different approaches in the churches' quest for peace, there also is beginning to be an exchange of methods and tactics.

Michaelson and several of his colleagues from Sojourners are involved in the leadership of the First Baptist conference this weekend. The conference itself is co-sponsored by the Church of the Saviour, a small congregation here that is closer to the iconoclastic Sojourners Fellowship than the establishmentarian First Baptist Church.

The Rev. Dr. Alan Geyer, a political scientist who heads a think tank at American University on the relationship between religion and politics, warned against "the danger of exaggerating the scope and significance" of a church-led peace movement at this time.

Nevertheless," Geyer acknowledged, "certain things are breaking out in a number of places."

Geyer, who was technical adviser to the American church delegation at the meeting with the Russian churchmen in Geneva, is concerned that churches not depend upon dramatic gestures.He said that he wants peace to become a continuing involvement for churches.

"The church needs to find ways beyond peace resolution and rallies to get people vocationally commited [to work for peace] for a lifetime," he said.

But for church leaders such as Coffin, who spends an increasing amount of time crisscrossing the county mobilizing for peace, the cause has become something of a holy calling.

"The nation needs help from the religious community - from the men and women who are less conformed to the ways of this world," Coffin said, paraphrasing scripture.

"We've only got a prayer" of avoiding nuclear holocaust, he declared, adding, "We've got to do what we can."