The Grapes of Wrath, written by John Steinbeck, has many parallel or recurring events throughout the novel, five of the major repeated themes would include the references to the Bible and Jesus Christ, the continuous praising of socialism, the changes that Ma goes through on the trip, and the changing definition of 'family' on the trip to and in California.
Beginning in chapter four, where Tom first meets Jim Casy, there starts a trend of religious references; the first major reference is Jim Casy singing 'Jesus is my Baby'. Jim is a retired preacher, who doesn't believe in the religion that he has been preaching all his life. Jim is a character who resembles Jesus Christ, a person who chooses to go on the road and be with the people. Jim doesn't act like he is better than the common man is, he wants to bring people closer together and stop humans from hurting one another. Casy sees the migrants as an army with out a harness, and thinks that he can bring everyone working together. In the climax of Jim's journey, he is killed in a scene extremely alike how Jesus died, Jim Casy, after he was hit in the head at the labor union meeting, "fell out of the light." The author was trying to show how a 'normal' person like Jim Casy could've helped turned the horrible migrant life around, and with him falling out of the light, it gave Tom a chance to step into it, and take control of things.
There were also many smaller religious reference in The Grapes of Wrath, for example, at the end of the novel, when Uncle John has to send Rose of Sharon's stillborn baby down the flooding river. This is a parallel to Moses, as a live baby being sent down the river to give hope to the town below. When Uncle John sends the dead baby down the river, he hopes that it will send a message to the people in California, about how wretched of a life the migrant workers have had.
This novel had many recurring references to socialism, beginning in chapter eight,