In The Grapes of Wrath, Steinbeck likens journey of the Joads to the exodus of the Israelites. Just as there are the Twelve Tribes of Israel, so too are there twelve Joads on the trip to the Promised Land: Ma, Pa, Tom, Al, Granma, Noah, Ruthie, John, Winfield, Rose, Connie, and Jim Casy. This journey from Oklahoma to California is analogous to the escape from Egypt to Israel in the Old Testament.
Jim Casy, of lapsed preacher, whose initials are "J.C." (for Jesus Christ) is the Christ-figure who will sacrifice himself to help the laborers and the one to show Tom the way.
Enotes says it best:
The biblical symbolism in John Steinbeck’s The Grapes of Wrath can be viewed as essentially messianic in nature. However, this is not to say that the message or point of the novel is in itself religious. Walter Fuller Taylor, in his commentary on the work, makes the relevant point that Jim Casy, a figure who is depicted in a very Christ-like manner by Steinbeck, actually denies any similarity between the Son of God and himself. Indeed, “the theology and ethic of Casy’s religion have little…to do withChristianity.”(1) All of life, as Casy conceives it, is unified in a holy transcendental soul whose capacity for goodness can be vitiated only by any act which has at its root individual selfishness: “But when they’re all workin’ together, not one fella for another fella, but one fella harnessed to the whole shebang – that’s right, that’s holy.”(2) The message of salvation that Casy brings and that Tom Joad carries forward is one of adaptation to the environment of the world. The constant reference is to an earthly salvation in which man can survive happily; the codes of behavior are natural actions. Steinbeck has none of his characters aspire to a higher spiritual plane. The hierarchy of values, as he dramatizes it, has been aptly cited as the need and dependency which man evidences in respect to the “primal elements (water, sun, fire, land) . . . sex, womanhood, family life, death, mutualism of spirit. . . .”(3) In short, the messianic word is an emphatic reminder of the individual’s place in the scheme of humanity. The only sin is failure to recognize such a relationship. As such, this message is not in the tradition of the Messiah.