Why did Jim casy give up being a preacher in Grapes of Wrath?

He felt he had sinned more than a preacher ought; what with his human weaknesses towards sex and less than 'preacherly' thoughts. In the same sense, he represents Jesus Christ. They both had the same initials, Jim had 12 people in the car when they left with the Wilsons, like Jesus' 12 disciples, and many other parallels. His dying Words were very similar to the Words of Jesus when he died on the cross. Jim Casy felt he was not connected to religion enough to be able to convey it across. His faith was lacking so thus he abandoned his religion (not entirely, so remember that for later within the book), but enough so that he remained a religious figurehead for the readers.