Throughout this novel Jim Casy, whose initials, J. C., clearly point to his Christ-like status, acts as the moral moutpiece of Steinbeck. The relationship between Jim and Tom is particularly interesting, as we that more and more Tom becomes influenced by Jim's example, finally deciding after Jim's death to pledge his life to living by the same kind of moral values that Jim himself lived under:
Wherever they’s a fight so hungry people can eat, I’ll be there. Wherever they’s a cop beatin’ up a guy, I’ll be there. If Casy knowed, why, I’ll be in the way guys yell when they’re mad an’—I’ll be in the way kids laugh when they’re hungry n’ they know supper’s ready. An’ when our folks eat the stuff they raise an’ live in the houses they build—why, I’ll be there. See? God, I’m talkin’ like Casy. Comes of thinkin’ about him so much. Seems like I can see him sometimes.
There is no clearer indication of the way in which Tom becomes Jim's disciple completely after Jim's self-sacrificial death. Tom becomes an individual who is able to look to the future, take responsibility for it, and act towards achieving the unity of mankind that Casy believed in. Even though Tom does admit that he may lose his life as a result of pursuing this struggle, he comforts Ma by saying that Jim Casy's spirit in him will live on and will never be vanquished.