SELLING BIBLES may have been akin to peddling snake oil when Flannery O'Connor wrote about the traveling Bible salesman who seduced a customer in order to steal her wooden leg, but Christian booksellers have long since become respectable and prosperous trademen in America's book business. Religious publishing, an industry that also produces gifts, records, and tapes, is approaching the billion-dollar-a-year mark. There are more than 6,300 Christian bookstores across the country, with an average of one new store being opened every day. Even as the New York stock market falters, the Christian marketplace remains bullish. And just as evangelicals constitute the fastest-growing religious group in the country, evangelical-oriented publishing is the fastest-growing sector of the book trade.

If Norman Vincent Peale were called on to describe the 32nd annual convention of the Christian Booksellers Association (primarily an evangelical affiliation) held in July in Naheim, California, he might devise an inspiring slogan based on the Seven P's of Christian Publishing.

The first p -- or principle -- would be for perennials: those titles that linger indefintely on the Christian bestseller charts. Bibles, of course, are the perpetual blockbusters, from variations on the traditional leather-bound King James version to the most recent favorite, the Living Bible, a simplified version that has sold more than 23 million copies since 1962. Zondervan, the largest and one of the oldest companies in the industry, is promoting its NIV (New Internation Version) in a new economy model. And once religious titles arrive on the best-seller lists, they can linger for years. Hal Lindsey's apocalyptic The Late Great Planet Earth , probably the best-selling Christian trade book of the '70s, is still on the Top 10 paperback list of Bookstore Journal , CBA's official publication. Returns on religious titles average only about 5 percent (often as low as 2 percent), and publishers' backlists are often bulkier than their new catalogues.

The second P is for paraphrase -- the knack of putting Jesus into the vernacular. Just as translations of the Bible have been progressively more idiomatic since the first stirrings of the Reformation, Christian literature has been getting more down-to-earth, as it were. People have been asking themselves what Christ would do in contemporary situations -- if, for instance he were to show up on a football field, a school, on TV. Althouth many conservative evangelicals hold the Gospel to be infallible, they are not averse to taking certain liberties with the scriptures for the sake of relevance. Jean E. Bender, for example, paraphrased Corinthians I:13 for the benefit of the CBA: "When I was a customer, I talked like a customer, I thought like a customer, and I reasoned like a customer. But when I began working in a Christian bookstore I looked at customers in a different light." The same willingness to "adapt" texts holds for other genres as well. There were not one but two Christian Mother Gooses at the convention. Majorie Decker, a British grandmother whose Christian Mother Goose Book has been on the best-seller list for 15 months, has taken the terror out of nursery rhymes by turning "Three Blind Mice" into "Three Kind Mice." There are also Christian whodunits, thrillers and fantasies, and there are Christian comic books, including an inspirational Archie series ("Archie's Clean Slate") and a version of Chuck Colson's Born Again .

The third P is for positive thinking, that best-selling upbeat genre popularized by Peale himself. While Peale continues to produce spinoffs of his original formula -- his new fall title for Revell Books is Positive-Imaging -- a number of other cockeyed optimists have invented their own versions of self-fulfilling prophecy. The most prolific of these is Robert Turn Your Scars Into Stars Schuller, whose weekly Hour of Power is telecast from the shimering Crystal Cathedral of Garden Grove, only a stone's throw from Disneyland and the Anaheim Convention Center. Schuller's newest title is Living Positively One Day at a Time .

Secular publishers have also gotten into the optimism business. Bantam Books, whose fledgling religious division turns out one or two titles a month, offers Og Mandino's The Greatest Success in the World . Modest titles are scarce in the Christian marketplace; Mandino's previous blockbuster was called The Greatest Salesman in the World .

The 7,300-odd exhibitors and buyers who attend the CBA convention had little reason to doubt these glowing scenarios of success, since this years attendance equaled last year's. That of the ABA, the CBA's secular counterpart, had declined significantly. While Christian books still account for only 5 percent of overall publishing market, sales have been increasing each year at a rate of about 16 percent. Christian publishing is itself a success story, as are the careers of many of the individual publishers and writers pedaling their wares. Millionaire Jarrell McCracken, for instance, whose Word, Inc., which was purchased by ABC in 1973, began his business with a single tape called "The Game of Life," a sports allegory in which Jesus Christ was the coach and the Bible the rulebook.

The secret of growth for Word and for most other successful companies has been diversification, which brings us to the forth P, actually a double P: products and promotion. Word now leads the industry in Christian records and tapes, and the company plans to put out its first catalogue of videotapes by early 1982. Other companies specialize in Bible-study aids and gifts. Much of the merchandise in the typical Christian bookstore might be more appropriate for Woolworth's than for Barnes and Noble. In addition to categorized book racks, the model store on display at the CBA featured rubber welcome mats with a rainbow motif; poster display racks; counters of inspirational T-shirts; portable trees of bumper stickers with mottoes like "In Case of Rapture This Vehicle Will Self-Destruct"; walls of greeting cards and records; and a corner for plaques, statuary, and jewelry -- items that would once have been considered too close to Roman Catholic tastes for comfort. The proliferation of this Christian version of pop culture has prompted evangelical writer Virginia Stem Owens to charge in a book called The Total Image that

"Where the spirit needs nourishing by dreams and visions, we are substituting the junk food of media hype."

The fifth P, not surprisingly, stands for personalities. Like secular culture, evangelical culture is cued to certain media superstars (like Billy Graham) whose books seldom fail to become best sellers. In recent years, as religious books have become a lucrative market, Christian-celebrity books, like country music, have experienced the "crossover" phenomenon. Big-name religious writers publish with secular housees, while famous secular role models (or criminals) published Augustinan confessions with religious houses and go on the celebrity revival circuit. Washington D.C. has produced a number of these latter-day confessors. Both Charles Colson's Born Again and Jimmy Carter's Why Not the Best became all-time best sellers. (Colson's book is still going strong, as is his sequel, but according to Broadman Press, Carter's book has not been selling for a couple of years.)

The most recent Christian book to emerge from the Watergate era is Leon Jaworski's Crossroads , an account of the Watergate prosecutorhs reliance on devine guidance at time of crisis, which proved only a modest seller at the convention. Nevertheless, Bill Bright, founder of the Campus Crusade for Christ, announced that the book will be sent to 4,000 government leaders. Said Jaworski, "I know of no reason why there should be a big problem with the use of the reigion in government centers." A local bookstore saleswoman said of the book, "It hasn't generated much interest out here; it takes a Chuck Colson for that."

Celebrity status, then, no longer guarantees instant success for a Christian book. Sales of Billy Graham's first book for word, "How to Be Born Again , fell far short of the company's optimistic record first printing of 800,000, and Jerry Falwell's Listen America sold only 20-25,000 copies in hardback. Christians are looking primarily for two seemingly disparate qualities in their inspirational literature; pragmatism and prophecy, the sixth and seventh P's. Graham's next book for word, Till Armageddon , an end-times jeremiad, has proved a blockbuster, as has Hal Lindsey's new Countdown to Armageddon (for Bantam). Brad Miner of Bantam observed,"We've gone beyond that born-again phase when people were into that exhilarating experience of finding Christ to a recognition that a lifelong commitment involves a thinking through of every aspect of one's life." Consequently, practical books, particularly about family problems, are the single best-selling category of Christian books. Family counselor James Dodson has five books currently on the best-seller list. Books about money, too, figure in this practical how-to or "cope" category.

If many of these trends seem confusing or contradictory, it's because the P that Peale wouldn't have considered prevails in the business of Christian literature: paradox. Some evangelicals call for simplicity, others for conspicuous prosperity. Some talk of sweetness and light and dress in bright pastels, while others preach the gloom and doom of Swinburne's pale Galilean. Some march for the Moral Majority, others are wary of it. Perhaps the most accurate P to describe the world of evangelical communications is pluralism.