The Sermon on the Mount
Blessed are the poor in spirit, for theirs is the kingdom of heaven.
Matt. 5:3 NIV
It’s just impossible! Absolutely impossible! I thought to myself as I read the Sermon on the Mount for the first time. I can’t, and no one can, live and obey Jesus’ directives in this sermon. Three chapters of loving those who hate you, laying down your life for those who persecute you, and forgiving those who have used you. Not only are Jesus’ words difficult to keep, but also, these admonitions should be obeyed out of love with a joyful heart. This sermon is impossible to live. But, that’s the rub.
We can’t live the Sermon the Mount in our own power. We must be poor in spirit desperately needing God’s strength in our weakness (Matt. 5:3). We must be mourners, a people who grieve the state of our fallenness yearning for help (Matt. 5:4). We must hunger and thirst for righteousness for we have no means within ourselves to overcome the world’s influences, sin’s grip, and the devil’s temptations (Matt. 5:6). The Sermon on the Mount is lived not by being adequate, but by being available. That is, available to Christ’s all-powerful and sufficient grace (2 Cor. 9:8; 12:9).
The Sermon on the Mount can only be lived by trusting Christ to live his life in and through us (1 John 4:9). Only Christ successfully lived the Sermon on the Mount and he can do it again in us (Col. 1:27). By summary, the Sermon on the Mount is what our lives look like when Christ is having his way in us.
Beware of placing our Lord as Teacher first instead of Saviour. That tendency is prevalent today, and it is a dangerous tendency. We must know Him first as Saviour before His teaching can have any meaning for us, or before it can have any meaning other than that of an ideal which leads to despair. Fancy coming to men and women with defective lives and defiled hearts and wrong mainsprings, and telling them to be pure in heart! What is the use of giving us an ideal we cannot possibly attain? We are happier without it.
If Jesus is a Teacher only, then all He can do is to tantalise us by erecting a standard we cannot come anywhere near. But if by being born again from above  we know Him first as Saviour, we know that He did not come to teach us only: He came to make us what He teaches we should be. The Sermon on the Mount is a statement of the life we will live when the Holy Spirit is having His way with us (emphasis mine).
Oswald Chambers, Studies in the Sermon on the Mount, electronic ed. (Hants, UK : Marshall, Morgan & Scott, 1996), 10.