Matthew 5.17 Jesus said, ‘Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfil them. 18 For truly I tell you, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished. 19 Therefore anyone who sets aside one of the least of these commands and teaches others accordingly will be called least in the kingdom of heaven, but whoever practises and teaches these commands will be called great in the kingdom of heaven. 20 For I tell you that unless your righteousness surpasses that of the Pharisees and the teachers of the law, you will certainly not enter the kingdom of heaven.

We live in an age where moral absolutes are rejected, even considered intolerant. The only sin is of being intolerant. So those who adopt this approach are intolerant at the intolerance of others! Especially those who disagree with them!

The problem with using society to decide what is right and wrong is that things change and terrible things may happen when wrong is tolerated, if not promoted. The holocaust is an example.
In The Interaction of Law and Religion, Harold J. Berman, professor of law at Harvard University. "If law is merely an experiment, and if judicial decisions are only hunches, why should individuals or groups of people observe those legal rules or commands that do not conform to their own interests?" (p. 28). The problem with subjective morality is people' selfishness.
It has been suggested that the Bible is out of date, but the truth is the opposite. The Bible is always relevant because people do not change and God does not, either. The Bible is God's perfect, eternal, and infallible Word.

Some say that the Bible is open to interpretation. That one person's opinion of it is as good as another's and there is no place for dogmatism. The idea is that people are free to believe or not and to follow, or not, any or all of Scripture as they wish. But, it is Scripture that will judge people, not the reverse. We see this in Jesus' teaching today. This is part of what we know as the Sermon on the Mount. Jesus saw God's word as true and authoritative. So did the devil, as we read in the temptation of Jesus in the preceding chapter!

Jesus started off the Sermon on the Mount with the Beatitudes, vs 3-8, talking about the character of believers. He then tells of the function of believers, as salt and light in verses 13-16. In today's reading, he teaches the foundation for the inner qualities of the Beatitudes and for functioning as salt and light.

Jesus came to fulfil the Law & Prophets, not abolish them. His was a new way but founded on the Old Testament. He revealed the true intention of God's will found in the Old Testament.
Jesus fulfilled the law in his person and actions. Jesus is perfect. He always followed God's ways. Every commandment He obeyed, every requirement He met, every standard He lived up to. He always loved God. He always loved others, putting other people's interests before his own. "The Son of man did not come to be served but to serve and give his life as a ransom for many," Mk.10.45. If we want to know what God is like, we should look at Jesus. If we want to know what we should be like, we should imitate Jesus.

Jesus fulfilled the law in his teaching. After today's reading, he goes on to unpack the true meaning of the law, which requires heart observance, rather than just outward obedience. He talks about committing adultery in one's heart. Divorce and marriage. Telling the truth. Not retaliating but loving enemies. Giving to the needy. Praying and fasting. Trusting God and not worrying. Not judging others.

In verse 20 he said, For I tell you that unless your righteousness surpasses that of the Pharisees and the teachers of the law, you will certainly not enter the kingdom of heaven.
Verse 20 is not part of today's reading, but I cannot see how you can separate this from verses 17-19. The Pharisees and teachers of the law were looked up to as being religious and moral. Jesus' followers must have been shocked to hear these words. But Jesus makes it clear that the transformation of someone heart is needed, not legalism that can lead to self-righteousness and condemnation of others. Only Jesus can change someone's heart to God by the work of the Holy Spirit.

 The prophet Jeremiah looked forward to this, 600 years before Jesus. 31.33 ‘This is the covenant that I will make with the people of Israel after that time,’ declares the Lord.
‘I will put my law in their minds and write it on their hearts.  I will be their God, and they will be my people. 34 No longer will they teach their neighbour, or say to one another, “Know the Lord,” because they will all know me, from the least of them to the greatest,’ declares the Lord. ‘For I will forgive their wickedness and will remember their sins no more.’

Believers' sins can be forgiven because Jesus fulfilled the ceremonial law by his sacrificial death on the cross. Something we celebrate and proclaim in this service. Sacrifice was at the heart of Israel's worship. Sin had to be paid for by sacrificing animals. Yet these sacrifices never had the power to cleanse anyone from sin. They were pictures of what the Messiah would do. The ceremonial law ended because it was fulfilled. Because the reality had come, the pictures and symbols had no more place or purpose. On the final Passover night of our Lord's life, He instituted new symbols to commemorate and proclaim His death.

Jesus has died once and for all, a perfect sacrifice to pray the price of sin. His resurrection showed that God had accepted this sacrifice. The tearing of the curtain to the Holy of holies (Mt 27.51) showed that the way to God is now open for those who are united with Jesus through the undeserved gift of trust in Him. Jesus has freed His followers from the power and the consequences of sin. We are free to respond by trusting in Him and living for Him.

Trusting by following His example, loving God and others.

Trusting by following His teaching, motivated by God's love to follow His will with our hearts and minds. Motivated by His Spirit within us. Inspired by the love, joy and peace He gives.

Trusting by knowing that on the cross He died for every one of us, so that we can know Him in this life and also look forward to being with Him in eternity "when everything has been accomplished."