A little more than a year ago a group of Northern Virginia Episcopalians, dismayed by changes in their church, formed their own church, St. Margaret of Scotland, to keep their faith, as they saw it, pure and undefiled.

Earlier this month some members of that church, dismayed by events at St. Margaret, formed their own church, St. Andrew of Scotland, to keep their faith, as they saw it, pure and undefiled.

Both churches, which meet at opposite ends of Alexandria, characterize themselves as "Anglican Catholics." Both are very clear about what they think the Episcopal Church, the only embodiment of Anglicanism in this country recognized by the worldwide Anglican communion, has done to despoil the faith.

Three years ago, at its national convention, the Episcopal Church voted to ordain women to the priesthood and tentatively approved a revised version of the Book of Common Prayer.

Some opponents of these actions maintained that such policies were so far outside "Anglican tradition that by adopting them, the church had placed itself outside the maintstream of the faith. The opponents said they had no recourse but to ordain their own bishops and set up a national church, the Anglican Catholic Church (Acc), to carry on what they consider the true traditions and tenets of Anglicanism. This movement led to the founding of St. Margaret.

But the breakaway Episcopalians quickly found it was easier to agree on what they opposed than what they supported. A constitutional convention of the ACC in Dallas last September spent so much time on acrimonious argument, walkouts and factional strife that delegates were unable to complete action on the new church's constitution.

Since that time, two bishops of the Anglican Catholic Church -- Bishops Peter F. Watterson of the Diocese of the Southeastern U.S., in Atlanta, and Robert S. Morse of the Diocese of Christ the King, on the West Coast -- have left the Anglican Catholic Church and formed a splinter group, called the Anglican Church in America.

Jerome L. Loomis, senior warden (top lay leader) at St. Margaret, said Sunday that the new split in the dissident Episcopal movement was a question of high church vs. low church worship styles. Others have indicated personality clashes were involved.

At any rate, St. Margaret voted July 8 to affiliate with Watterson's diocese, which has headquarters in Atlanta.

A number of members resigned on the spot and had orginized St. Andrew before the week ended.

"We are going to stay with the Anglican Catholic Church," said Francis T. Slate, a founder of St. Margaret who switched to St. Andrew, where he is junior warden.

"We consider that (the Episcopal Church) has left the church," he said.

"They've thrown over the Prayer Book, they've ordained priestesses and ordained the halfway people" -- a reference to homosexuals.

By opting for the Anglican Catholic Church, he said, "We consider ourselves the continuing church."

At St. Margaret, Loomis defended the action of his congregation in affiliating with the "high church" Watterson faction.

"We are a Catholic parish," he said, using the term to connote a liturgy compjrable to the Roman Catholic mass.

Last Sunday, 55 persons turned out for the 9 a.m. service at St. Andrew, which is using the facilities of a United Methodist Church of the same name, just below Alexandria Hospital.

At the Ramada Inn across town, 30 were present for St. Margaret's 11 a.m. service. At least one woman attended both services.

It was difficult to distinguish between the two congregations. Both were all white, overwhelmingly middleaged or older. Each followed scrupulously the Book of common Prayer, and each celebarted the annual Scottish games in Alexandria the day before with bagpipe music.

Loomis, an alexandria attorney, declined to disclose the annual budget of St. Margaret, which had its first meeting in February 1978, but he did say its major expense was $500 monthly to rent the meeting room.

"I wouldn't want this to get out, but money has never been a problem for us," he said.

Asked about mission and service programs of the congregation, which meets only blocks from an area of extreme poverty and decay, Loomis responded, "We have made vestments for other (Anglican) Catholic parishes; we've contributed to certain monastic orders and to the travel expenses of priests who couldn't get to conferences without it."

He said the St. Margaret Congregation plans to be in its own church building by next Easter.

St. Andrew will continue sharing space with the Methodists for a while, officials there said.

Methodists, incidentally, are spiritual descendants of a former Anglican, John Wesley, who in the 18th century began a new movement to keep the faith pure and undefiled. CAPTION: Picture 1, Matthew F. Kuldell, first piper of St. Andrew of Scotland Church in Alexandria, leads the recessional at services of the new Episcopal splinter church.; Picture 2, Leaders of the breakaway St. Andrew of Scotland Anglican Catholic Church Francis T. Slate, junior warden; the Rev. A. Fraser MacCommond, and Donald Baldwin, senior warden, discuss their church and its plans. By Gerald Martineau - The Washington Post