Insiders and outsiders
The most obvious abstract imagery in the novel is the tight-knit community that exists in Raymond among the religious folk. Then, all the sudden, Jack Manning shows up, and the community realizes they are unlikely to accept him. The imagery is a portrait of "us versus them," because it proves to the reader that this community is formed in an insulating way. Instead of being like Jesus, they have become like the very religious community that Jesus was persecuted by.
Jesus's example
The reverend in town encourages his community to consider the "example" of Jesus by asking them all to submit an answer to the question, WWJD? What would Jesus do? The outcome is that they are forced to understand a new abstract imagery, one that is literally shaped by Jesus's opinions and behaviors. Jesus was undeniably accepting to the bottom-feeders in society, so they must also demonstrate that in their lives.
The church
The church is a form of imagery, both concrete and abstract, because the church operates as a singular vessel for a universal church authority, so that the church building and the people that comprise "the local church" are literally depictions of a religious organization. They literally are a religious organization, so that the church is a visual reminder of the social order imposed by the historical influence of Christianity.
Anxiety and fear
The fear that shapes this community makes them traditionalists in more ways than just politically. They struggle to be open to change. They are actually averse to change, so that they have a heightened sense of the status quo. They have firm opinions about "the way things are," and "the way things should be." When things don't obey those orderly systems that they impose onto reality, they get really upset, so that the reader can see they are being governed by paranoia and anxiety.