We will use Matthew 5:1--7:29, the canonical account of the Sermon on the Mount, as our text. Rami and I, of course, are aware of long-standing discussions related to the text. For our purposes, however, it matters little whether the existing text reports a condensed version of an occasion or is an edited compilation of various sayings of Jesus. We are interested in exploring the sermon's possible meanings.
The Beatitudes describe those who follow the way of Jesus, while the saying about "salt and light" speaks to the nature of his followers' influence in broader society. The specific teachings which follow provide pointed,though not exhaustive, illustrations of how following Jesus might play out in daily life. The challenge and depth of the sayings will become evident as we deal with them.
Christians have long debated how to apply the sermon. At the risk of oversimplification, I tend to reduce the range of options to a handful.
(1) A considerable segment of Christianity tends to assume the sermon applies only to a special class of Christian, perhaps clergy or monks or such. Everyday Christians are not expected to live up to such a standard. This viewpoint has existed at least since the Middle Ages.
(2) At any given time, some Christians treat the sermon as Jesus' agenda for social change. For example, classic American liberal theology assumed the sermon described what society would be like once the kingdom of God came to maturity within history.
(3) Others maintain the sermon was meant to apply only within a very limited time frame. They may differ over the time frame in question. American dispensationalists, for example, traditionally argue the sermon applies only between the return of Christ and the end of world.
(4) A long-standing approach assumes the sermon's demands are really designed to expose our sin, shatter our pride, bring us to repentance, and draw us to rely on God's grace.
(5) Some Christians argue the sermon has no application in this age. Instead, it describes the life of the redeemed in heaven or in the new creation.
(5) Christians from a variety of theological stripes take the sermon's demands seriously, assume they can not be fully realized in this life, yet insist we must try. Such Christians assume they live under God's grace. Generally, they also assume the sermon is meant to apply to the community of God, though such ideals might positively affect the world at large as well. The sermon, thus, always informs the life of the Christian individual and the Christian community. This is my favored approach.
Rami, all of the above represents a drastic simplification of an extremely complicated picture. To borrow and modify your earlier illustration, wherever three Christians gather to discuss the Sermon on the Mount, there shall be five opinions. That being said, I think I've provided a platform from which to launch our conversation.