The 461st anniversary of the start of the Protestant Reformation will be observed in a variety of ways this Sunday by area churches. Though Reformation Day actually falls on Tuesday, most observances will take place on Sunday. Reformation Day commemorates the posting of the 95 theses by Martin Luther, an Augustinian monk, on the doors of the Wittenberg Cathedral in Germany.

The principal observance is a Lutheran Reformation Festival, sponsored by Lutheran congregations in the metropolitan area at the Washington Cathedral. Featured speaker at Sunday's 4 p.m. service is Dr. Ralph W. Lowe, director of the department of religion at the Chautauqua Institution near Buffalo, N.Y. Several choirs, a brass ensemble and handbell choir will present a pre-service musicale at 3:30 p.m. The public is invited.

The Downtown Cluster of Congregations will present a Reformation Fall Festival on Sunday, from 1 to 3 p.m., at Library Square - on G street between 9th and 10th streets NW. An ecumenical group of 15 area churches will participate in the event that will include strolling musicians, choirs, drama, clowns, craft displays in addition to many other exhibits and events.

Dr. Lowe also will be the featured preacher at a Reformation Day service at 8 p.m. Tuesday at St. Peter's Evangelical Lutheran Church, 1725 Michigan Ave. NW. The service will be a translation of Mertin Luther's German Mass of 1526.

A Reformation Day Celebration will be held at 6 p.m. Sunday in Northwood High School auditorium, 919 University Blvd., Silver Spring. Dr. Joel Nederhood, speaker on the internationally known "Back to God Hour" radio broadcast of the Christian Reformed Church, will be the speaker. The occasion is sponsored by area congregations belonging to the Christian Reformed, Orthodox Presbyterian, Presbyterian Church of America and Reformed Presbyterian congregations.