Potok's journey toward light; The Book of Lights, by Chaim Potok. New York: Alfred A. Knopf. $13.50.

The many lights in Chaim Potok's "Book of Lights" shine with allegorical splendor. In his descriptions of tenement fires in a decaying Brooklyn neighborhood, the flash of the first atomic bombs at Alamogordo and Hiroshima, and the "light that is God" of mystical Jewish texts, Potok writes of luminous truths and darkly threatening evils.

An ordained rabbi and doctor of philosophy, the author is well acquainted with both tradition and doubt. Like his previously acclaimed novels, "The Book of Lights" is the story of an American Jew's search for identity and faith in the 1950s.

To all appearances, Gershon Loran is a serious young seminarian headed for the rabinate. He studies hard and is well liked by his professors and classmates. He worships daily with the aunt and uncle who raised him and takes dispassionate walks along the Hudson River with the daughter of a famous rabbi.

Behind the sober visage, however, smolder the fires of a mystic. In dreamlike visions, Loran imagines conversations between Talmud scholars who "would like the world to be smooth and rational" and Kabbalists who are "filled with poetry and contradictions." In his study of ancient Jewish mystical writings known as Kabbalah, Loran finds texts full of "dangerous imagery and ideas," full of chariots of fire and heavenly lights. Are these writings nonsense or the soul of Judaism? He's not sure.

Loran has always lived in the shadows of great thinkers whose promise, for him, has ended in tragedy: his parents who set out to build a new life in Israel , only to be killed in a street riot; the great Jewish physicists who helped to develop the atom bomb, who "held in their hands the light of creation -- and returned to the world the light of death."

When Loran opts for an Army chaplaincy after graduation, he begins to emerge from these self-imposed shadows into a world of glaring needs. He gradually finds dignity and strength in the Koreans he at first had despised, and, as he travels throughout the Orient, he finds himself "being taught the loveliness of God's world by a pagan land."

It's a flicker of understanding, and not surprisingly Loran wants more. At the close of the book, he goes to Jerusalem to find his Kabbalah professor from his seminary days. In Kabbalah he hopes to find the questions of light and challenging dark that he can devote his life to answering.

A story that draws much of its meaning from ancient Hebrew writings could be perplexing, if not boring, for the non-Jewish reader. But Potok cares too much for the ideas he's setting forth to lose them in abstract reasoning. We're caught up with Loran's questions because they're the questions we all have to answer. His quest isn't exclusively Jewish -- it's a quest for the things of the spirit.

In a narrative style that's an intriguing blend of one-word sentences and flowing stream-of-consciousness paragraphs, Chaim Potoc mixes intellectual probing and irreverent humor in equal parts, to keep his message from slipping into a soulfur or guilt-driven apologia. He's writing about issues of the heart here and should attract readers who have hearts, not just card-carrying believers.