There is a difference between building a home and building a house. There is a difference between being faithful to a spouse and simply staying married to the same person. There is a difference between being a good driver and never having an accident.
There is a similar difference between upholding laws and fulfilling the law. The state law is there to be upheld. God's Law is given to be fulfilled. Beneath the words "abolish" and "fulfil" in today's gospel are two very different approaches to the Law which God gave to his chosen people Israel. The word translated "to abolish" has the sense of annul, repeal, or declare invalid when used with respect to law. The gospels record that Jesus was often criticised for not keeping particular laws such as those concerning the Sabbath. There must have been many people who saw him as completely disregarding the Law of Moses. Now the very same word is also used in the sense of pull down or dismantle a building. In fact it is the word used for the destruction of the Temple. As Christ hung upon the cross the passers by derided him, calling out, "You who would destroy the Temple and build it in three days, save yourself!" (27.40). Although a different word is used to speak of the destruction or killing of Jesus the word used here echoes throughout the gospel and is there as Christ hangs on the cross. In fact it is others and not Jesus who are the subjects of this word for destruction in the gospel.
The word used for "fulfil" is used by Matthew to talk about the coming into being of that to which the scriptures point. For example the flight into Egypt is said "to fulfil what the Lord had spoken by the prophet, "Out of Egypt have I called my son." (2.15). It is used also of the sufferings of Christ. For example after his betrayal and arrest, Jesus tells his disciples, "But all this has taken place, so that the scriptures might be fulfilled" (26.56). But here in his great sermon on the mount, Jesus is saying much more. It isn't just about prediction and fulfilment. He is the one to whom the whole of scripture points and for whom Israel longs. He is the fulfilment of God's covenant with Israel. This lived relationship comes to its fullness in the paschal mystery. What follows then are examples of how Jesus lives out that covenant relationship as one of us.
The distinction between merely upholding the Law and actually living the Law in its deepest sense expresses in concrete terms just who Jesus is and what we ought to be about as his disciples. We are about something which runs much deeper than acts such as murder, adultery or realities like lust and anger. It looks to how we stand in relation to God. It is about what is really going on between me and the God who made me and who can count "even the hairs of your head" (10.30). It is about how I respond to God's tender and particular care for me. Such a response ought to be nothing less that whole hearted.
So often in so many areas of our lives we can just get by, maybe through luck or maybe through cleverness and shrewdness. But we are called to so much more than merely not getting into trouble of one kind or another. Indeed the grace of God won't keep you out of "trouble". In fact, it might well get you into trouble! God’s grace and mercy are not simply aids to help us keep up appearances. It calls us to that depth of character and authenticity, which makes Jesus and those who would follow him "the salt of the earth" and "the light of the world".
In fulfilling the Law Jesus invites us to a relationship that is grounded not in our conduct or in our misconduct but in our faith in him and his faithfulness to us. He calls us to live in His creative and redemptive love not merely as in a house but therein to make our home.