For Tim Tebow, speaking at the First Baptist Church of Dallas, Texas, had to look like a great opportunity. He grew up attending a large Southern Baptist church, and an invitation to speak at one of the most venerable and historic Baptist churches in the world had to look like an easy call. He was going.

All that changed yesterday when Tebow, the National Football League's most prominent evangelical symbol, sent word through Twitter that he was withdrawing from the event. His sudden announcement came after a whirlwind of controversy over his scheduled appearance at the Dallas church. Its senior minister, Robert Jeffress, is no stranger to public controversy. His sound bites are often incendiary, but his convictions—including the...