Why does Casy not profess to love Jesus?

Casy tells Tom that part of the reason he quit preaching was that he too often succumbed to temptation, having sex with many of the girls he Œsaved.' Finally he realized that perhaps what he was doing wasn't a sin, and there isn't really sin or virtue ­ there are simply things people do. He realized he didn't Œknow Jesus,' he merely knew the stories of the Bible.