The legend of the Lamed Vov stretches back through ancient Hebrew mythology to the days of Babylon. It states that in every generation there must be at least 36 anonymous righteous men to justify the continuing existence of the human race. Otherwise, the world will simply come to an end.

Howard Fast, in his new novel "The Outsider," traces the life of a modern Lamedvovnik in the turbulent 25 years following World War II. Chaplain David Hartman had almost decided to leave the rabbinate and go into medicine when his Army unit liberated Dachau. The horror of it had seared his soul with images that would attack his dreams for the rest of his life, and sealed his future as a rabbi.

Within six months of his discharge he has married Lucy -- a beautiful Jewish-atheist USO volunteer -- and accepted a $1,200-a-year post as rabbi of a new congregation in rural Connecticut.

The Hartmans become fast friends with the Congregational minister and his wife, Martin and Milly Carter. The two men ponder the deep questions of faith, godliness, what drives men to become men of God, and they march in civil rights rallies and anti-Vietnam demonstrations. The women raise the kids, try to make do on clergymen's salaries, and establish their own female networks. Bar mitzvahs; the first funeral; the vandalizing of the synagogue; one synagogue member going to jail after refusing to name names before the House Un-American Activities Committee, another masterminding the bombings in Vietnam -- the panorama of national events merges with the problems and friendships of daily life.

In 50 years of being published, with more than 40 books to his credit, Howard Fast is known for his storytelling prowess and his probing of the defiant spirit of America's greatness. And there are many beautifully written, compelling sequences in "The Outsider." Yet in too many instances his narrative techniques are decidedly awkward.

About halfway through the novel, David asks Martin: "In the ten years you've known me . . . how many petitions for civil rights have we signed, how many antiwar demonstrations, how many peace vigils?" Martin replies, "Quite a few." Imagine, we've just covered 10 years of this man's life, yet this is the first we've heard of all those happenings. This exchange also illustrates the stilted quality of many conversations throughout the book -- as though they were created for the edification of the reader rather than being real discussions between friends.

Fast's saint is almost impossible to live with. Although Lucy's humor, common sense, and wide-ranging talents are critical to David's success, he ignores her emotional needs, shuts her out of his activities, and then complains that she doesn't understand him. Yet in the end, through authorial fiat, Fast rewards David and punishes Lucy. It hardly seems fair to treat such a nice person so shabbily.

For many readers, however, the major impact of the novel will be found not in David's physical and spiritual odyssey, but in two explosive passages dealing with President Harry Truman. The major episode involves the judge of the Rosenberg spy trial who, supposedly tortured by the prospect of sentencing fellow Jews to death, comes to David for advice and spiritual solace. Judge Interman (a fictitious character) describes how he was called to the White House and shocked by Truman's flat order: " 'Judge Interman, I want you to sentence them to death.' " Later, after Interman argues with him, Truman "just studies me for a while, and then he says, 'It's pretty damn good, being a judge, isn't it?' . . . 'a Jew judge, that's something.' "

One may say or write almost anything about the dead, and most of us are perfectly comfortable with Shakespeare's brilliant and historically inaccurate portrait of Richard III. But this is a description of a modern president. We need to know whether Howard Fast, author of "Citizen Tom Paine" and longstanding left-wing radical, who was jailed for contempt of Congress during the McCarthy witch hunts, who was one of the first to suggest anti-Semitism in the Rosenberg case, and who kept vigil at the prison the evening of their execution -- we need to know if Fast is savaging Truman out of personal and political hatred, or whether he really has information that researchers of the most recent spate of books on the Rosenberg case were unable to unearth. Too many people are willing to take at face value the historical distortions that abound in popular fiction, film and television fare.

There is a bland, split-personality quality about "The Outsider." Fast's hero is gentle, kind, spiritual and courageous. But he is a man without passion, except perhaps the passion of despair. Yet Howard Fast appears to be, still, an angry man with great passions. And an angry man writing about the passive purity of a saint (however flawed) is almost a contradiction in terms.