After Jesus was baptized by John and spent 40 days in the wilderness being tempted by the devil, He traveled through Galilee teaching “in their synagogues…proclaiming the gospel of the kingdom and healing every disease and every affliction among the people” (Matt 4:23). He was so popular that a large crowd followed Jesus and “seeing the crowds, He went up on the mountain, and when He sat down, His disciples came to Him. And He opened His mouth and taught them…” (Matt 5:1). What Jesus said to His disciples was the greatest sermon ever preached. It is commonly called the Sermon on the Mount and is found in Matthew 5-7. While Jesus spoke in the presence of a large crowd (Matt 7:28), His primary audience was His disciples (Matt 5:1).
The setting for the sermon was intentional. Jesus sat on a mountain with His disciples gathered near. Just as the Lord delivered His law to the Israelites on Mt. Sinai (Ex 19), Jesus sat on a mountain to deliver to His law to His disciples. In Exodus 19, the Lord gave His Law to the Israelites concerning who they are and how they should live in the Promised Land. In Matthew 5-7, the Lord gave His Law to the disciples concerning who they are and how they should live in the Kingdom of God.
The Sermon on the Mount is about the Kingdom of God
Jesus’ first recorded messages centered on repentance of sins and the arrival of the Kingdom of God (Matt 4:17 & Mark 1:15). Jesus talked often about the kingdom of God in parables (see Matt 13), but what is it? A kingdom is the dominion of a king. It is where a king is acknowledged and served; the area he rules and reigns. Therefore, the kingdom of God is where God is acknowledged and served as King. Jesus is the King of Kings and Lord of Lords (Rev 19:16) who instituted His kingdom when He came to Earth. The kingdom of God is best understood as “already, not yet”. The kingdom of God is already here as Jesus rules through and over the Church (those who are in submission to Him). The kingdom of God, however, is not yet fully implemented. The completion comes when Jesus returns a second time to destroy the devil and sin and to defeat the last enemy: death (1 Cor 15:26). At the time the kingdom of God will be throughout the world. The Sermon on the Mount must be understood as concerning the kingdom of God.
The Sermon on the Mount is about
Living in the Kingdom of God
The Sermon on the Mount is clear, authoritative teaching from Jesus about life in the Kingdom of God. The theme of the sermon is righteousness (e.g., about right living in the kingdom of God). Daniel Doriani summarizes the Sermon on the Mount as: “law, but much more than law. It tells us what we should do, but it also describes who we are and should be. It proves our character and invites us to see the world in a new way, as Jesus sees it.” Let us consider this closer:
The Sermon on the Mount tells us Who We Are
Speaking to His disciples in the presence of a large crowd was intentional. The message is to Jesus’ disciples but Jesus wants the message to be heard and understood by all. The Sermon on the Mount is focused on righteousness: His righteousness. We must not conclude that the Sermon on the Mount gives us an unattainable standard of righteousness that simply leaves us miserable. No, we must read the Sermon on the Mount with the gospel of Jesus Christ in view. While we cannot attain to Christ’s perfections on our own, His grace is sufficient for us. Therefore, let us hear the words of Christ and act on them (Matt 7:24). Christians are able to come to the Sermon on the Mount joyfully because Jesus is our righteousness. Jesus did not come “to abolish the Law or the Prophets…but to fulfill” (Matt 5:17). Jesus is the One whose “righteousness surpasses that of the scribes and Pharisees” (Matt 5:20). We enter the kingdom of God by hearing Jesus’ message: by repenting of our sins and believing that Jesus is the Christ. We are Christ’s disciples; redeemed, righteous and holy.
The Sermon on the Mount tells us How We Should Live
Being redeemed by Jesus, we are a new creation (2 Cor 5:17). The result of being saved means that we have a new attitude and a new way of living. We are to be holy as God is holy (1 Peter 1:16) and we are called to living a righteous life. Jonathan Pennington summarizes the Sermon on the Mount well when he wrote: “it’s wisdom from God, inviting us through faith to re-orient our values, vision, and habits from the ways of external righteousness to wholeheartedness toward God. This isn’t ‘law’ but “gospel.” Jesus is inviting us into life in God’s kingdom both now and in the future age. This is grace.” We come to the Sermon on the Mount with joy that we can glorify God with our body; in our thoughts, words, and actions.
Doriani concludes: “Once we see how the Sermon on the Mount leads us to the gospel, its beauty and authority remain intact, but its burden is lifted. Jesus’ words reveal His will, His character, and His grace. His will we cannot perfectly follow, and His character we cannot perfectly attain, but His grace is sufficient for those (in the language of 7:21-23) who call on His name with a sincere desire to know Him and be known by Him.”
 The kingdom of heaven and the kingdom of God are synonymous.
 Doriani, Daniel The Sermon on the Mount, pg. 9
 Pennington, Jonathan, https://www.thegospelcoalition.org/article/3-things-didnt-know-sermon-mount
 Doriani, 12.