“I do not know what the future holds, but I know who holds the future," the Georgia businessman said. "And I trust in God.”
Cain, 68, was a brief front-runner for the GOP nomination in 2011 but dropped out, before any actual votes were cast, in early December of that year.
Cain got a rise out of the crowd when he taunted the media and liberals whom he blamed for his ouster.
"The liberals thought that they had shut me up," Cain said as the crowd rose to its feet. "I'm back!"
Interestingly, Cain's performance was a virtual repeat of his speech before the same crowd four years ago, when he teased his 2012 presidential run -- the "dark horse" -- before walking off stage.