"I will continue to use the platform God has blessed me with to bring Faith, Hope and Love to all those needing a brighter day," Tebow wrote.
The Rev. Robert Jeffress, First Baptist's pastor, confirmed in a phone interview that Tebow called him Wednesday night to cancel.
Jeffress said Tebow told him he would like to speak at First Baptist at some point, but "he needed to avoid controversy right now for personal and professional reasons."
Jeffress has preached that gay sex is sinful, Mormonism is a cult and Islam promotes violence and pedophilia. He said Thursday that First Baptist was being mischaracterized as a "hate church," and that the church's teachings were consistent with historic Christian beliefs.
Tebow wasn't going to speak about anything controversial, Jeffress said.
"We had planned for him to speak very positively about the difference Jesus Christ had made in his life," Jeffress said.
Tebow won two BCS championships and the Heisman Trophy at Florida, but he has struggled to make it in the NFL. He barely played last season after the Jets traded for him from the Denver Broncos, where he started much of the season in 2011 and won a playoff game.
Tebow is a devout Christian who has built a large following through his faith. He has addressed church audiences before. Last year, he spoke to about 15,000 people gathered at an outdoor Easter service north of Austin.