17-year-old Joseph Joiner, a Northwest Florida racecar driver, has joined UMobile’s Twelve23 Movement. Joiner and his family have adopted the movement’s philosophy of specifically transforming the United States by spreading the gospel. Joiner and his family committed to the Twelve23 vision after hearing UMobile president Mark Foley speak to Hickory Hammock Baptist Church, Milton, Fla. Joiner and his parents share…