Much of the debate in the two-man play, "Mass Appeal," which opened at Ford's Theatre last night, deals with the fine line between truth and tact. Author Bill C. Davis has two men of the cloth from different generations arguing the question of selling out principle for popularity--mass appeal, if you will--but the serious moments of confrontation between the two men are, in a way slighted; the characters pull back for more jokes and the tears are quickly dried.

At times, it is an interesting case of a playwright who sometimes seems to have missed the message of his own play.

For most of the play, the technique works: It is funny without losing the issues of morality and survival that it puts on the table. But there is one moment near the end of the play that characterizes its main weakness--the older priest, Father Farley, punches his young charge out of frustration, a sudden lash of anger and misery at his own failings--and immediately makes a gag out of it. It seems a moment where the playwright is going for glibness, the laughter, and what should be a climactic moment is diffused.

Father Farley is the beloved gray-haired parish priest who takes on a feisty young seminarian, Mark Dolson, who is in danger of being bounced for his opinionated obstreperousness and a preseminary history of sexual dalliances. Dolson is convinced that he doesn't "attack, I express my opinion," but he is really quite obnoxiously earnest.

Farley, on the other hand, is a modern-day executive priest, buzzing his secretary on the intercom, rehearsing his homilies into a tape recorder and describing his pastoral work in categories like "three identity crises, seven divorces and three 'I-don't-know-why-I'm-alives.' " He also has developed the habit of the white lie, the "harmless" half-truth, to extricate himself from awkward situations, and it is clear he regards the priesthood as something of a pleasant sinecure.

Farley practices "song-and-dance theology." He is the kind of priest who measures his sermons by the coughs in the congregation and is always ready to provide cursory attention to current problems without really confronting them. Dolson, on the other hand, is gripped by life's agonies without being able to really love the ordinary people to whom he must minister. The bond that develops between them is the backbone of the plot, as they grapple with Dolson's ineffective resistance to the church institution and Farley's saddening realization of how far he has "lost Christ." The debate is brisk, and the questions worth asking.

Milo O'Shea has been playing Farley for nigh on three years now, and he controls the stage like the pilot of an airplane. He has a rubbery face that dances jolly until it cracks, and the skill to prevent Father Farley from being just a lovable old priest but a man with inner torment as well. As his foil, Adam Redfield tries extremely hard to be as strong a presence. He is earnest and forceful, but at times mechanical and stiff, a performance that has all the right moves but has not transcended them. His well-scrubbed looks are an asset, the young searcher still literally wet behind the ears.

"Mass Appeal" is an excellent piece for Ford's intimate stage. And if it delivers the message with a bit more sugar than is really necessary, the play still offers a moving and involving evening. The direction, by Geraldine Fitzgerald, is intelligent and skilled, and the script is literate.

"Mass Appeal," by Bill C. Davis, directed by Geraldine Fitzgerald; setting by David Gropman; costumes by William Ivey Long; lighting by F. Mitchell Dana. With Milo O'Shea and Adam Redfield.

At Ford's Theatre through April 3.