The Sermon on the Mount gives us a remarkable insight into the mind and heart of Jesus. Many of the things which he says in the Gospels echo words from the Old Testament. Yet Jesus never simply repeated truths from the past: he always presented new aspects to ancient truths or raised the Old Testament teaching to a higher level of truth. When he says "You have heard the commandment" and adds his own comment, he does not deny the truth of the commandment but widens its scope.

Psalm 119 begins with the affirmation "Happy are they whose way is blameless". Several Psalms repeat this teaching that we are called to a blameless life. Jesus certainly would not have denied this teaching, but in his Sermon on the Mount he is asking for a higher level of perfection. Jesus' demands are built on the Old Testament, but we are people with whom God, through the mediation of Jesus, has made a new and eternal Covenant. The newness of the Covenant enables us, with God's grace, to strive for greater perfection: "You must be perfect as your heavenly Father is perfect".