A coalition of evangelicals is holding a conference on nuclear arms next week in Pasadena, Calif., but one of the scheduled speakers doesn't know if he can make it. The conference will be neutral on nuclear arms, but Jim Wallis of Washington isn't. Wallis, who believes civil disobedience is necessary in stopping the arms race, may be in jail.

Wallis, founder of the Washington-headquartered Sojourners, a social justice evangelical group opposing nuclear arms, plans to demonstrate Monday with as many as several hundred others in the Capitol rotunda against nuclear arms.

The ecumenical demonstration will consist of walking into the rotunda, reading church statements against nuclear arms and praying. But demonstrations, however mild, inside the Capitol are illegal.

The civil disobedience is one aspect of a growing religious movement against nuclear arms.

Church and Jewish denominations in recent months have been bolstering antinuclear statements with national conferences and study materials for local congregations, and religious groups are beginning to band together in the movement. Many of the materials are beginning to tie into other global economic and justice issues in a peacemaking emphasis.

The tie-in of global issues is integral, said the Rev. Alan Geyer, a United Methodist minister who directs the Churches' Center for Theology and Public Policy, a Washington-based think tank funded by mainline Protestant, Roman Catholic and Orthodox groups.

While a concentration on the "just war" theory has been in the limelight in recent months, what may emerge from the antinuclear movement is a "just peace" theory as well, he said.

Activities are varied across the country:

* At the Capitol, religious bodies have mounted a twice-a-week team effort of Protestants, Catholics and Jews since March to lobby more than 100 borderline congressmen for a nuclear freeze and against first strike nuclear weapons.

* In Norwich, Vt., an ecumenical project called Bridges for Peace, formed after local United Church of Christ efforts in sparking nuclear freeze resolutions by town councils across New England two years ago, has reached into international territory.

It sponsored a delegation of nine Soviets through the Soviet Peace Committee to visit homes and churches in two New England states. In September, it plans to send representatives from the New England churches to churches in the Soviet Union.

* In St. Louis, the ecumenical Institute for Peace and Justice is promoting family support groups across the country to help parents teach their children peacemaking.

Churches and families are using the institute's book "Parenting for Peace and Justice" as resource material. Thirty thousand copies have been sold over the past two years.

* Across the country, seminaries and church groups are intensifying study of war and peace issues.

For example, a half dozen of the nine Boston-area Protestant and Roman Catholic divinity schools that form the umbrella Boston Theological Institute teach peace theology courses. The institute last year hired its first coordinator for peace education programs ranging from lecture series to training sessions for teachers. "It's never been this widespread and widely based," said Cynthia Holshouser, the coordinator.

The most widespread activity is virtually unseen: study groups at local churches struggling to understand the issues.

"This is not a group that said I'm going to conduct a march, I'm going to nail a paper to the White House gate," the Rev. John Mingus, pastor of the United Church of Christ of Seneca Valley in Germantown, said of a study group he led at his church this spring.

Every Monday night for eight weeks, a dozen congregation members from 15 to 83 years old gathered to follow their denomination's new "Peace Futuring" course. The course leads study groups to contemplate a peaceful 21st century and to work out their own steps of how the world can get there.

In one session, the Germantown group took Maryland and Virginia as examples of jurisdictions dealing with disputes with each other through law instead of warfare and applied that to a global perspective.

"Peace will not come from on high but from people saying all over we've had enough of the way things are, that there are options in terms of achieving peace," Mingus said.

The U.S. Roman Catholic bishops' adoption this month of a 150-page pastoral condemning nuclear arms is expected to give added political weight to the movement.

The document breaks from the U.S. church's immigrant-related tradition of uncritical acceptance of U.S. defense policy. Using an extensive analysis of the just war theory, the pastoral condemns use of nuclear weapons, calls for a "halt" to the nuclear arms race and accepts nuclear deterrence only as an interim step while disarmament steps are worked out.

Meanwhile, the Union of American Hebrew Congregations, an organization of the country's 760 Reform synagogues, last month issued a 307-page manual analyzing Jewish theology and listing resources to mobilize support against the nuclear arms race. The manual had 1,500 prepublication orders from all three branches of Judaism.

Protestant churches have been sharing peacemaking material. The Catholic pastoral is expected to cross denominational lines as well: The United Methodist bishops this month recommended Methodist congregations study the pastoral as well as Methodist material.

The Lutheran churches, like the Roman Catholic Church, come from a tradition uncritical of U.S. foreign policy but also have issued statements at odds with U.S. defense policies. They include an American Lutheran Church call for a bilateral U.S.-Soviet nuclear arms freeze and even a suggestion for the U.S. government to move toward some unilateral steps in the interim.

One barometer of church commitment is designation by Protestant denominations of full-time national and local peace coordinators.

"War-making can't proceed as it has in the past," said Canon Charles Martin, coordinator of the Episcopal Diocese of Washington's new peace commission.

Since September, 50,000 copies of the Episcopal Church's antiwar document "To Make Peace" have been distributed across the country, and three-fourths of the church's dioceses have established peace commissions.

Even churches leaning toward the "peace through strength" position, which views continued nuclear arms development as a necessary safeguard against Soviet aggression, are studying the issues from both sides.

The predominantly conservative National Association of Evangelicals debated the nuclear freeze issue for the first time at its annual conference this year. That did not go unnoticed; President Reagan wooed the group in an address asking that delegates support his defense policies.

The association also is among co-sponsors of the evangelical conference on "peacemaking in the nuclear age" in Pasadena next week, the first major conference on nuclear arms held by evangelicals. The conference will present both sides and take no stand, but even holding it is considered remarkable.

"Twenty years ago, evangelicals didn't get into public issues of the day. They thought that politics and religion don't mix, that politics is the reality of the sinful world," said Richard Cizik, legislative researcher for the association's Office of Public Affairs in Washington.

The Sojourners-sponsored demonstration at the Capitol on Monday, which will include a legal demonstration outside the Capitol as well as the civil disobedience, will be ecumenical--Protestant and Catholic church groups are sponsoring delegations from across the country.

The event will lead into a week of antinuclear ecumenical events across the country sponsored by a coalition of the National Council of Churches and other organizations, ending with an interfaith peace sabbath next weekend sponsored by still other groups.

Meanwhile, shifts in thinking are spawning more studies and terminology. Members of the traditional peace churches--the Quakers, Church of the Brethren and Mennonites--historically have been accepted as conscientious objectors.

Many mainline Protestant churches adopted policies during the Vietnam War trying to legitimize conscientious objectors in their own churches to the government. The effort had little success with the government, but the churches resurrected their aid during draft registration calls in recent years.

The United Church of Christ last year appointed a committee of theologians to study the feasibility of designating the church as either a "pacificist" church or a "nuclear pacifist church." Among study aspects will be conscientious objection specifically against participation in a nuclear war.