A colorful Bethesda pastor who has been active in affairs of the National Capital Union Presbytery has left that body to start a new church, which will be part of a new denomination made up largely of dissident Presbyterian congregations.

The Rev. Eddy Swieson, 50, for 18 years associate pastor of Fourth Presbyterian Church in Bethesda, will conduct the first worship service of the Christian Covenant Church tomorrow at 10:30 a.m. The church will meet in the Thomas S. Wootton High School in Potomac.

During his years at Fourth Presbyterian, Swieson built a substantial following, particularly among young adults, for his skill in organizing and teaching Bible classes.

When the Rev. Dr. Richard Halverson resigned as senior pastor of Fourth Presbyterian last year to become the U.S. Senate chaplain, Swieson was barred from succeeding him by a Presbytery regulation that automatically excludes such a succession.

"We didn't want to lose Eddie from this part of the country," explained Richard T. Meyer, a layman, "so a number of us devoted followers of Eddie and his Bible classes decided we ought to start a new church with him as pastor."

Swieson and the "core group" of supporters, which Meyer said totals about 75, had proposed that the new congregation be a part of the Presbytery, and received encouragement from the Rev. Dr. Edward White, Presbytery executive, if the new church would be established in the northern part of Montgomery County.

"The Presbytery was enthusiastic about supporting Eddie in starting a new church where we need a new church . . . , in the Gaithersburg area, where most of the growth is, not in the lower part of the country where there isn't any growth," White said.

The Presbytery's New Church Development Committee in mid-June formally notified Swieson and his supporters of their backing for a new church in the Gaithersburg area. But "the core group said 'no way,' " Swieson explained. "Most of us live in this Potomac-Rockville area and the need here is obvious."

Swieson, who was born in Indonesia of Chinese Buddhist parents, is a colorful and popular speaker in evangelical circles. His autobiography, "When the Angels Laughed," details how as a newborn he was coaxed back to life after his desperately poor parents had decided to let him die of starvation; his triumph over disease, warfare and Japanese occupation of his native Java, his conversion to Christianity and his postwar career as an evangelist and radio preacher and evengelist, first in the Orient and later in this country.

Swieson and his new church have affiliated with a two-year-old denomination, the Evangelical Presbyterian Church, which Swieson said included "about 60 congregations," most of them breakaways from the United Presbyterian Church.

"I feel sad," Swieson said. "I have been with the UPC denomination 18 years . . . up to the General Assembly level."

"I feel very sad about the whole thing," said White. "I'm very fond of Eddy personally."