As the days turned cold in the winter of 1986, the telephone calls started coming into little St. Paul Baptist Church in Capitol Heights: single parents, often working for minimum wages, couldn't pay their rent and were about to be evicted.

The scene repeated itself in churches all over Prince George's County, and a handful of clerics began talking about what they could do to prevent such people from landing on the street. The result, announced yesterday by church officials, is the formation of the Interfaith Eviction Relief Fund, an unusual collective effort by Protestant and Catholic churches, the county government and business organizations.

The $100,000 fund, which is administered by a private agency, United Communities Against Poverty, provides a maximum grant of $500 to county residents, earmarked for families or elderly people facing eviction. Supplemented with $250 of county money per case, and with counseling, it may enable recipients "to retreat from the edge of poverty," said the Rev. Bruce Eberhardt, rector of the Episcopal Church of the Nativity in Camp Springs.

The group supported its announcement with figures from the county showing that nearly 3,000 families were evicted in 1985, the last year for which complete figures were available.

"There are a lot of social changes taking place in this county -- new housing and industrial development," said the Rev. Tom Pollard of Holy Spirit Catholic Church in Forestville. "But not everyone is sharing in the boom."

The need for emergency housing -- growing nationally as the amount of subsidized housing declines -- precipitated what several church leaders said is the first major ecumenical social campaign for churches in Prince George's. In years past, Catholic and Protestant clerics have been unable to do much collectively because they were divided on several issues, including abortion, the leaders said.

"We didn't even know each other's names," Pollard said, adding that this same group is now exploring advocacy work together on several issues.

The Rev. Bob Williams, St. Paul's minister, supports the idea of advocacy. "The church can't solve all society's problems through its own resources," said Williams, who received calls last winter from 10 families facing eviction from one apartment building.

For several of the church's leaders, the eviction fund has been their first experience with a broad fund-raising appeal. They quickly discovered that learning each other's names was a lot easier than making people reach for their pocketbooks, or working through a government bureaucracy.

Beginning last summer 1986, they approached congregations in the southern part of the county, asking for $600 a year. They contacted 100 churches and synagogues, according to Eberhardt, and raised about $30,000 from 38 churches. They plan to turn their attention now to congregations in the northern end of the county.

At the same time, they negotiated with the County Council and County Executive Parris Glendening to match whatever they raised from their congregations. A written chronology distributed yesterday hints at some of those frustrations:

Last February, for example, the church officials planned to meet with a representative of Glendening's: "We went directly to his office, but he was out. We asked him to call." Also in February, they were told they were "late with the proposal" for the coming year's county budget; in March, they went before the council where they received a "welcome but noncommittal response."

The business community was the slowest to respond, church leaders said, but yesterday the county and private enterprise came through.

As television lights flooded the community room at Forestville United Methodist Church, Glendening handed Eberhardt a large Styrofoam facsimile of a check for $30,000, signaling the county's first-year commitment. Various business leaders, including an ebullient spokesman for the Apartment and Office Building Association, presented checks totaling $22,000.

"There's $15,000 more coming," said the association's Stephen Goldberg. "The only thing wrong with this idea is I didn't think of it."

Church leaders later said that the fund has been running as a trial since April. Twenty-eight families have been served, they said; 40 families did not meet the criteria set up by the community agency administering the program.

Some people turned away from the fund may, eventually, end up back at the churches' doors, said the Rev. Richard Fowler, a Methodist minister who works for the Catholic Archdiocese of Washington.

"We don't have any illusions that we're meeting all of the need," Fowler said. "What we must work toward is more decent, affordable housing. We must not lose sight of that."