Jerome Light is a middle-class, upstanding, married, family man who happens to be an atheist. When no one is home one evening, Jerome watches as his house is swallowed and destroyed by a sinkhole. His insurance company says he is not covered for this Act of God. Unable to sue the insurance company or God, Jerome decides to sue a television evangelist named Gideon Calhoun, who regularly says he is "God's agent here on Earth." A dashing, mysterious attorney named Thaddeus MacConnell takes the case.

Jerome and Gideon are given surprising mandates from their attorneys. Jerome, the atheist, must prove in court that God exists, and that Gideon is God's agent. Gideon, the evangelist, must argue that he is not God's agent, and that God may not even exist!

The families of both men are pulled, sometimes against their will, into this epic battle that changes everyone's life forever.