In both the gospels of Matthew and Luke, Jesus delivers a famous discourse, which is usually called the Sermon on the Mount. For centuries readers have acknowledged the beauty of its high ethical standards. What is not noticed very often is how Jesus weaves into a whole cloth what we would today call private morality and social justice. Along with the well-known prohibitions against sexual lust in the heart, adultery, and divorce there are calls to give to the poor (Matthew 6:1-4) and to refrain from overwork and materialism (Matthew 6:19-24).
In Western society these sets of concerns have often been split off from one another. In fact, each of America’s two main political parties has built its platform on one of these sets of ethical prescriptions to the near exclusion of the other. Conservatism stresses the importance of personal morality, especially the impotence of traditional sexual mores and hard work, and feels that liberal charges of racism and social injustice are overblown. On the other hand, liberalism stresses social justice, and considers conservative emphases on moral virtue to be prudish and psychologically harmful. Each side, of course, thinks the other side is smug and self-righteous.
It is not only the political parties that fail to reflect this ‘whole cloth’ Biblical agenda. The churches of America are often more controlled by the surrounding political culture than by the spirit of Jesus and the prophets. Conservative churches tend to concentrate on one set of sins, while liberal ones concentrate on another set. Jesus, like the Old Testament prophets, does not see two categories of morality. In Amos 2:7, we read, ‘They trample the heads of the poor; father and son go in to the same girl.’ The prophet condemns social injustice and sexual licentiousness in virtually the same breath (cf. Isaiah 5:88ff). Such denunciations cut across all current conventional political agendas. The Biblical perspective sees sexual immorality and material selfishness as both flowing from self-centeredness rather than God-centeredness.”
— Tim Keller, Generous Justice