In my opinion, this is a story about Jesus, who was somewhat of a Vonnegut topic. The main character, Eliot Rosewater, is an intensely altruistic figure who devotes his life to helping the less fortunate. Although he could obviously have great power, he chooses to live his life in a hotbed of sin and vice known as Rosewater County. It is apparent that his people endow him with almost messianic qualities and expect him to remain with them forever. However, under repeated criticism and attempted exploitation by his lawyers, he is eventually removed and put in a mental hospital.
Other similarities suggest themselves, too: at the close of the book, Eliot declares all children of Rosewater County to be his legal children, mirroring the statement that "we are all Christ's children." One (unseen) character in the book is Mary Moody, a probable prostitute who claims her children to be Eliot's as well. And Eliot (who, incidentally, claims not to be religious) is called on to baptise the children at one point. Near his "crucifixion", Eliot experiences an Armageddon-like hallucination. Even Eliot's name, Rosewater, has mystical overtones and could be taken as alluding to wine or blood. Finally, Kilgore Trout claims that he shaved off his beard when he got his job because of the "sacrilege of a Jesus figure redeeming stamps." This shows that Vonnegut had something of Christ and sacrilege in mind during the novel's writing.
In my opinion at least, Vonnegut's goal here was to reintroduce Christian ideas from a more modern (his modern) perspective. The similarities between Rosewater and Jesus are obviously there, and so it is surprising that, despite Vonnegut's cynicism, he included so many respectful religious references in the novel. Perhaps his cynicism was, this time, not directed at Jesus himself, but at the public's reception of him. This point remains open.
What else is this novel supposed to show us? Aside from Vonnegut's usual character-interaction subplots, there is a marked difference between rich and poor. Although both often seem foolish and wanton, the author is clearly calling the reader's attention to class distinctions. There is also a discussion of conservatism vs. socialism -- Eliot persists in foolishly giving his money to the poor and thus "squandering" his father's fortunes. However, when Eliot is put in an expensive sanatorium, his father realizes that his old lifestyle in fact cost less.
It is finally worth mentioning that, like Kilgore Trout, Eliot Rosewater often has cameos in other Vonnegut books. For example, Billy Pilgrim meets him in a hospital in Slaugherhouse Five, and he funds the fateful art convention in Breakfast of Champions. However, these appearances do not support the themes addressed in this novel, but only serve to advance the plot. | 
