On the cover of Your Best Life Now, Joel Osteen flashes the sort of smile that suggests a man who not only succeeds in everything but also quietly befriends the world's outcasts. Osteen has much to smile about: His first book showed up on The New York Times bestseller list for hardcover advice books in November, and by mid-January it had reached No. 1—outranking even Rick Warren's The Purpose-Driven Life.

With Warner Faith expecting to sell at least 2.4 million copies of his book, Publishers Weekly has already dubbed it a crossover phenomenon. The Your Best Life Now Journal is due out this month.

What will devotees of advice books find in Your Best Life Now? The standard fare is there: More uses of must, should, the imperative voice, and start-your-morning life affirmations than would be tolerable in anything other than an advice-filled bestseller. What keeps the text from feeling like an upbeat lecture is Osteen's consistent tone of love and pastoral concern.

Osteen writes at length about his father, John, who founded Lakewood Church in Houston. The elder Osteen died in 1999, and Joel—one of five children—felt an unexpected interest in stepping into the formidable pulpit his father left behind. The church's membership has tripled since then, surpassing 30,000.

Osteen's teaching avoids some of the harder edges of prosperity theology, such as Kenneth Copeland's bizarre emphasis on Jesus' "dying spiritually" in hell or his scowling mockery of Christians who haven't grasped the core prosperity doctrines. Still, Osteen promotes some of prosperity theology's favorite notions, such as reprogramming your mind with positive thoughts or changing your life with the power of your spoken words. He writes of his mother's ...