The Sermon on the Mount opens with the identification of what the blessing of God requires. These requirements of life are summarized by what we call the beattitudes, character traits expected by God even in the Old Testament. It continues by disabusing the hearers of false notions about what God expects of his people and promptly moves to some commands that have to do with our relationship with God.
The sermon ends much as it began: with a call to obedience. At the start of the sermon (5:19) Jesus said: “Anyone who breaks one of the least of these commandments and teaches others to do the same will be called least in the kingdom of heaven, but whoever practices and teaches these commands will be called great in the kingdom of heaven.” Here, Jesus says “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but only he who does the will of my Father who is in heaven.”
Often, the “Kingdom” is confused with the Church, and admittedly, it’s an easy mistake to make. The New Testament teaches that those in one are in the other. That both started at the same time. That admission to one is the same as admission to the other. But when it comes to Matthew, Jesus is obviously talking about two different things. The first readers of Matthew are already in the Church, but Jesus is pointing to something else: the kingdom of heaven – something beyond this life. It is safe to say that those of the Christian age not in the Church will never be a part of the Kingdom of Heaven. On the other hand, it is possible to be a part of the Church, and still miss the kingdom of heaven.
Who will ultimately enjoy the kingdom of heaven? Those whose lives reflect the rule of God in the here and now.