DENVER — This is the story of three sports-loving Muslim brothers and how they boosted the career of the NFL’s most famous Christian. The Suleimans - Tariq, Ali and Mohammad - are responsible for “the Sign,” the towering electronic billboard that captured national attention when it began running messages in September urging the Denver Broncos to start Tim Tebow as quarterback. It worked. “It just goes to show you,” said Mohammad, “when Muslims and Christians get together, miracles can happen.” Now the talk of professional football and a pop-culture phenomenon for his unorthodox style, onfield heroics and highly visible Christian...