A decade ago, book publishers discovered a fertile market in the growing number of liberal-minded Jews interested in Buddhist meditation—the publishers called them "JewBus." Rodger Kamenetz started the craze with a book called "The Jew in the Lotus: A Poet's Rediscovery of Jewish Identity in Buddhist India," and soon Jewish meditation centers were open all over the West Coast. Meditation, the JewBus argued, did not detract from their Jewishness; rather, their identity was enhanced by the practice, by silent reflection and a mental reaching out toward God.

Fast forward. Janine Turner, formerly of the television show "Northern Exposure," has just come out with a DVD called "Christoga: Yoga Filled Body … Christ Filled Soul." The DVD promises that a regular Christian yoga practice will "improve your ability to perform activities of daily living." In Alabama, a woman named Susan Bordenkircher teaches thrice-weekly yoga classes at her Methodist church—classes that are sometimes filled with as many as 60 or 70 people—and last year published a book called "Yoga for Christians" with a major Christian publishing house. In Arizona, a woman named Deanna Smothers last year started Yahweh Yoga, which, among other things, offers certification programs for people who want to be trained in Christian yoga. What makes the yoga Christian in most cases is simply this: the teachers replace chanting in Sanskrit with the saying aloud of Bible verses; they ask their students to dedicate their practice to Jesus.

Some orthodox Jews didn't like the JewBus, and some fundamentalist Christians don't like Christian yoga practice. Yoga, they say, has its roots in Hinduism—an ancient religion that is, among other things, polytheistic. It is impossible to blend the two without violating the First Commandment, these Christians say. That's why Laurette Willis developed exercises called PraiseMoves, which look like the ancient yoga asanas, or positions, but aren't: Willis's poses have names like Angel and Prayer Warrior, and each is tied to a specific verse in Scripture. Willis believes that yoga is the dangerous entry point for a lot of non-Christian beliefs, including New Age superstition and astrology. Pope Benedict XVI might agree. In 1989, as Cardinal Joseph Ratzinger, he wrote that some spiritual practices, including yoga, "can degenerate into a cult of the body." The "pleasing sensations" one gets from yoga, he said, should not be confused with "spiritual well-being." But is it idolatry? Only your inner god knows for sure.