TONGUES OF FIRE The Explosion of Protestantism in Latin America<i> by David Martin(Basil Blackwell: $39.95; 256 pp.) </i>

In his introduction to “Tongues of Fire,” David Martin, a professor of sociology at the London School of Economics, promises not to write like a sociologist. “I have tried to be simple,” he says. “The technical language . . . can be converted to ordinary speech. . . . I want to present a world of (human) actors, as well as of (social) processes.”

If he had only done as he promised, this book would be welcome. The growth of Protestant, particularly Pentecostal, sects in Latin America since 1960 has been a phenomenon almost too big to grasp. An overview is sorely needed. Country by country, from Chile and Argentina to Puerto Rico and Mexico (with illuminating side trips to Korea and South Africa), Martin tries to explain how 40 million people have become Protestants in what used to be exclusively Catholic territory.

What has happened, he says, is that Anglo America has won its 400-year war with Latin America. The unity of church, state and culture that was broken in 17th-Century England and northern Europe (and utterly dissolved in the United States) is finally showing cracks south of the Rio Grande. This is especially true, he says, in countries such as Brazil, where the Catholic Church has been weakened while the culture, enriched by native and African beliefs, remains essentially religious.

In these countries, Martin says, poor people, blacks and Indians identify Catholicism with alien oppressors. Even “liberation theology” is tainted by its intellectual origins. Yet the poor also reject the secular, Marxist opposition that church-state unity has bred. Protestantism appeals to them for its connection with U.S. prosperity; for its sobriety and peacefulness, as opposed to violence and machismo; for its simple, biblical message, and for the way it lets lay people participate in the church and communicate directly with God. The Pentecostals appeal the most because they stay closest to the grass roots and because their emotional forms of worship echo those of pre-Catholic faiths.

Martin tackles several provocative issues: What is the link between Protestantism and economic success? How does the appeal of the U.S. life style offset fear of U.S. cultural imperialism? How does “backward” religion displace the sophisticated kind? Most provocatively, he suggests that what once seemed a worldwide secular trend may be reversed in this century by conservative Protestantism, Judaism and Islam. But a book needs readers to stir debate. This one is unlikely to find many, relying too heavily on secondary sources and written in a leaden tongue.