THE HIGHEST ALTAR: The Story of Human Sacrifice <i> by Patrick Tierney (Viking: $22.50; 480 pp.) </i>

Journalist Patrick Tierney has stuffed three books into a single set of covers here; any one of them would be a notable achievement. The first describes his travels to Chile and Peru to report on the startling finds of “high-altitude archeology.” Climbers in the Andes have come upon the ruins of Inca ceremonial sites atop peaks as high as 21,000 feet. At some of these sites, archeologists have found the mummified bodies of children buried alive as sacrifices to the gods. Tierney accompanied local experts on treks to hitherto unexplored mountains. Having survived dizzying ascents and sudden storms, he emerged with the outlines of a complex system of belief that, he shows, has survived the centuries since the Spanish conquest.

But the climbs were only Tierney’s warm-up. During his six years in South America, he found evidence that Indian tribes are still conducting human sacrifices. Like Carlos Castaneda in search of Don Juan (but without the peyote visions), he cultivated Indian shamans called machis and yatiris to learn the truth about three such incidents. A five-year-old boy in southern Chile was slain in 1960 after an earthquake and tidal waves had devastated his village. A young man was ritually beheaded in 1986 near Lake Titicaca in Peru as a way for smugglers and cocaine dealers to magically increase their wealth. And in the same year, a 9-year-old boy in an evangelical Christian community in Chile had a stake driven through his heart to exorcise “demons” from his sick grandfather. These sacrifices, Tierney concluded, were only a few of many directly related to Inca and pre-Inca rites.

In the third strand of his narrative, Tierney went to Israel to track the spoor of human sacrifice in our own cultural history. “Blood sacrifice,” he asserts, “is the oldest and most universal act of piety.” All societies have practiced it, he says, not just to appease the gods but to channel and restrict human violence. In a provocative reading of the Bible, he credits Old Testament Judaism with being the first religion to reject human sacrifice. Christianity, he says, reinstated it, at least symbolically, with the Crucifixion and the body and blood of the Eucharist--thereby regaining a primitive power that appealed to Andean shamans. All this can be argued with. But Tierney undeniably and in clear, sober, sensitive prose has left behind him a monument to high adventure, high risk and high-altitude thought.