BOOK REVIEW : Faith and Doubt: A Fine, Subtle Account : VIPER TREE<i> by Joseph Monninger</i> Simon & Schuster $18.95, 267 pages

Set on the savannas of sub-Sahara Africa, Joseph Monninger’s “The Viper Tree” gives a fierce natural authenticity to a story that blurs the lines between miracle and magic, between the Christian supernatural and the powers of native animism.

It is not a heart of darkness, although there are some fearsome depths in Monninger’s story. It is a chiaroscuro. His characters do not reject a Conradian “Other”; they try to understand it as best they can, move with it to the degree they can and, above all, let their awareness of it live in their own lives without destroying them.

The book begins with the present-day report of a Jesuit priest sent from Rome to investigate a claim of sainthood. Mother Marie, the aged superior of an African mission, has called for the beatification of Frederich Loebus, a stranger who arrived at her mission 50 years earlier, stayed a while and disappeared. The report attaches three accounts which make up the story: Loebus’ journal, Mother Marie’s own account and the testimony of an American expatriate named Hawley.

Loebus, as he appears in the first part, is a naked man, a human tabula rasa who arrives in the story bereft. He is a European stripped of his history; Africa will create him as the biblical God created man: by blowing its breath on his dust.

An Austrian, he deserted the German army during World War II after serving in a firing squad that executed three Jews. He bribes the crew of a Portuguese freighter to take him to South America; instead, he and four other refugees are thrown overboard just off the West African coast. Villagers in canoes converge on them; two of the Germans, taking rescue for threat, swim away and drown. The others are brought ashore, fed and given a hut to live in.

In the village, Loebus experiences the first of the manifestations that will straddle Mother Marie’s testimony of miracles and the animist mystery of the African shamanistic cults. When he goes out with the villagers in a fishing canoe, a herd of dolphins suddenly appears, driving the fish before them and providing a bumper catch.

Later, having been taken prisoner by the Tuareg tribe, Loebus attacks their chief and is given a humiliating punishment. A goat skin is attached to his back and his arms are lashed behind him. He must pick up his food with his teeth and lap up water. “I have made an animal of you,” the chief tells him. “I believe you are a goat. Perhaps you will be a goat for me.” It is degradation but it is also something else. Animals represent magic, as well; when Loebus revives a drowned child by artificial respiration, the natural and the supernatural seem to merge.

Monninger has written so that Loebus’ voice is something other that human. It is powerful and evocative. Loebus, like an oracle, speaks with no sense of himself; we hear through . We wonder what he is becoming.

Here Mother Marie takes up the account. She writes of her time as a novice in the mission with three other nuns. Loebus, who has escaped from his captors and made his way through the jungle, is taken there almost dead. Sister Marie is drawn to him, for which she punishes herself by stinging her hand with a scorpion.

The nuns see a saintly power in this strange, near-silent figure. When the local French prefect comes to arrest him as an enemy national, they try to give him sanctuary. Eventually they yield, but before Loebus can be taken away, he escapes. Odd things happen: The animals at the mission had been restless during his stay, and after he is gone, the prefect is persistently tracked by a pack of baboons, one of which he had shot.

In the last part, which takes place 30 years later, Hawley, who has been working on an irrigation project in the area, tells of being taken to see a man who has arrived in the village, who seems to be a priest and who is dying. “Protect me,” he whispers in Hawley’s ear and expires. A little later, his body disappears.

This was Loebus, it seems. He had been living far in the back country and had acquired the reputation of a revered shaman, or nyanga ; maker of animal fetishes with formidable powers. Hawley finds that he is thought to have received these powers. Despite his skepticism, he feels strange forces at work in his mind. In the company of a local priest, he hunts for the dead man’s body and finds himself dueling a powerful and near fatal magic.

Hawley’s story, although it has its strengths, doesn’t maintain the power of the first two parts. The rrail of Loebus as full-fledged shaman lacks the mysterious ambiguity of the earlier portions when we see him moving between worlds.

But the author’s achievement in these first two parts is remarkable. The nuns and priests at the mission are drawn with an extraordinary fineness and humanity. It is hard to think of another writer since Graham Greene who has written such a subtle and affecting characterization of faith and doubt. In this case, the doubt is not disbelief, but the inroads of an animistic universe so different from that of the Christians.

Next: Elaine Kendall reviews “Curtain” by Michael Korda (Summit Books).