Be faithful in your giving and God will reward you financially. It's not always stated that blatantly but the promises of the Prosperity Gospel--or the name-it-and-claim-it gospel, the health-and-wealth gospel, the word of faith movement, or positive confession theology--are false. Yet its message permeates the preaching of well-known Christian leaders: Joyce Meyer, T. D. Jakes, Joel Osteen, Creflo Dollar, Kenneth and Gloria Copeland, and many more.

The appeal of this teaching crosses racial, gender, denominational, and international boundaries. Why are otherwise faithful Christians so...