Why would two devout Christians cling to their faith despite their doubt?

Why would two devout Christians cling to their faith despite their doubt? Author Richard Rodriguez and scientist Sir John Houghton take viewers deep into their personal beliefs and questions about their own faith. Rodriguez, a life-long Catholic, has remained in the church even though it condemns his homosexuality. Houghton has remained a believer despite his allegiance to the discipline of science that demands proof and the evidence of trial and error. "One of the most important statements you should be prepared to make as a believer is: I don't know,"says Houghton.