The Republican governor plans to join thousands of fellow Christians Saturday in The Response, a day of prayer, fasting and repentance at Reliant Stadium in Houston.
America is facing economic and social crisis and "people adrift in a sea of moral relativism," Perry has said. "That's why I'm calling on Americans to pray and fast like Jesus did."
An atheist group sued to keep Perry from participating in The Response in his official capacity, the Houston Chronicle reports. A judge rejected the claim, and Perry has not spelled out his role in the event.
Groups organizing the rally include the American Family Association of Tupelo, Miss., which crusades against pornography, gay rights, feminism and evolution, and the International House of Prayer of Kansas City, Mo., whose founder, Mike Bickle, warns his followers of a Satanic religion called Harlot Babylon arising in the last days he sees coming.
"I believe that one of the main pastors of the Harlot movement ... is Oprah [Winfrey]," Bickle has said. "She is winsome, she is kind, she is reasonable. She is utterly deceived."
In a speech last month, Perry said: "I truly believe with all my heart that God has put me in this place at this time to do his will."