"One can't leave all the good music to the devil" says Luke Callender, the 20-year-old bass player of a Texan heavy metal band. He's making music for Jesus at Cornerstone, the annual Christian rock festival in Illinois where 30,000 fans camp out for a week of punk, hip-hop and prayer. No sex or drugs obviously, but lots of rock and roll. "By using punk-rock, we spread the Gospel to people who would otherwise not listen". Cornerstone Festival in Bushnell, Illinois is the largest annual gathering for Christian Rock in the world, attracting 30,000 fans for a week of worship alongside heavy metal, punk and hip-hop in America's Bible belt.