Sex is out; self-improvement, the family and physical fitness are in, and romance is on the horizon.

That, in a nutshell, is the current trend in the $1-billion-a-year world of Christian publishing, whose wares were laid out this week for the 34th annual convention of the Christian Booksellers Association.

Nearly 9,000 religious booksellers thronged the 4 1/2 acres of exhibits at the D.C. Convention Center every day this week. After daily 8 a.m. devotional services, and in between workshops on such topics as "How to Sell Bibles" and "Are Computers the Answer?" the booksellers ranged the exhibit area to restock their shelves with everything from "The Christian Mother Goose" ($11.95) to Scriptures Cookies ($4.50 a doz.), 14 karat gold Holy Spirit tie tacs ($98) and "Walk With Jesus" shoe strings ($2).

Not surprisingly, the Bible, available today in more than 100 versions and translations, is still the best seller in the nation's 5,400-plus Christian bookstores. But within the last decade or so, both secular and religious publshers have discovered the fertile and loyal market of evangelical Protestantism.

Booksellers from around the country and publishers attending the meeting here agreed that the explosion of evangelically oriented sex manuals of a few years back has been supplanted by books on family topics.

In addition, publishers' lists this year are bulging with self-help volumes with such titles as "It Takes So Little to Be Above Average," "Seeds of Greatness," "Improving Your Self Image," "Dare to Discipline Yourself," and "Good Guys Finish First." Though they are aimed at a Christian readership, most of the works lean harder on pop psychology as the ground for success than on prayer.

Taking their cue from the popularity of romance novels in the general book trade, several religious publishers are coming up with less steamy versions for the evangelical trade. There'll be no bed-hopping and no sex outside marriage, said Zondervan Press' Paul Hillman of his company's new Serenade line being launched next month. "They'll be good 100 percent romances, like romance novels used to be," he said.

And while the books will "indirectly have a religious element," he explained, "We don't have people quoting Bible verses at each other. You don't do that in real life."

While religious books and Bibles are the mainstay of Christian bookstores, these establishments are also the supply line to that segment of the populace that delights in proclaiming its religion from lapels, coffee mugs, key rings, Frisbees, memo pads, walls.

John One Ten of California offered high-fashion sports shirts and sweaters that displayed, instead of a toney alligator on the left breast, a chaste dove or fish, both Christian symbols. For more flamboyant believers with more enthusiasm than taste, there were T-shirts in Da-Glo colors proclaiming "JESUS 83."

There were religious plaques for every taste in ceramic, wood, cross stitch and print, including one that proclaimed: "Honey, God Don't Sponsor no Flops."

A representative of Augsburg Publishing House said his company had just concluded a deal with a major discount chain for a line of children's wear imprinted with the colorful characters of Augsburg's "Dear God" series of children's books.

There were gimmicks galore. "Sermons in Chemistry" is what Allen Berg of Portland, Ore., called the $75 kit he was selling. To a vial of muddy liquid--"original sin"--he added a few drops from the vial of red, and the murk turned crystal clear. "That shows the cleansing power of the blood of Jesus Christ," he explained. Other mixes, he promised, would illustrate Jesus' turning water into wine, Pilate washing his hands, and more than 40 other Bible lessons.