Throughout the letter, King makes references that fellow clergymen would be familiar with, making his case in an idiom they will understand. There are references to the Apostle Paul, to Saint Augustine, to Thomas Aquinas, and to Jesus Christ. He also makes it clear that he, like they, wishes to avoid violence, pointing out that his strategy of nonviolence is a much palatable option for southern whites than many black nationalists, who he says have "concluded that the white man is an incorrigible 'devil.'"
King speaks of his concern for the church itself, pointing out that if Christians do not take a moral stand against the evils of Jim Crow, they risk irrelevance:
If today's church does not recapture the sacrificial spirit of the early church, it will lose its authenticity, forfeit the loyalty of millions, and be dismissed as an irrelevant social club with no meaning for the twentieth century.
At the end of the letter, he affirms his brotherhood in the Christian faith with the ministers he is addressing, saying that he hopes "that circumstances will soon make it possible for me to meet each of you, not as an integrationist or a civil-rights leader but as a fellow clergyman and a Christian brother." Much of the letter is spent expressing his disappointment that these men, who he says he expected to support him, have instead chastised and criticized him. In this way, he is both expressing common cause with them as one minister to several others and calling them to think about their duty as men of the faith. This is a constant theme of the letter, reminding them what true Christians have done in the past, and asking them, in not so many words, to consider what position on segregation would be consistent with their religious faith.