Today, we listen to the Lord saying: «Do not think that I have come to remove the Law and the Prophets (…) but to fulfill them» (Mt 5:17). In today's Gospel, Jesus teaches us that the Old Testament is part of the Divine Revelation: First, God made himself known to men through the prophets. The chosen People gathered on Saturdays in the synagogue to listen to God's Word. And just as a good Jew knew the Scriptures and put them into practice, we Christians should frequently meditate —if possible, every day— upon the Scriptures.
In Jesus we have the plenitude of Revelation. He is the Verb, God's Word, that has become flesh, and dwelt among us (cf. Jn 1:14) to let us know He is God and how He loves us. God wants of man a response of love, expressed upon the fulfillment of his teachings: «If you love me, keep my commandments» (Jn 14:15).
We can find a good explanation of today's Gospel in St. John's first letter: «For this is the love of God, that we keep His commandments. And His commandments are not burdensome» (1Jn 5:3). To keep God's commandments means that we truly love him through our deeds. Love is not only a feeling; love also wants deeds, deeds of love, to live the double precept of charity.
Jesus teaches us the malice of scandal: «Whoever breaks the least important of these commandments and teaches others to do the same will be the least in the kingdom of heaven» (Mt 5:19). Because —as St. John says— «the man who says, ‘I know him’ but does not do what he commands is a liar, and the truth is not in him» (1Jn 2,4).
At the same time, He shows us how important good example is: «On the other hand, whoever obeys them and teaches others to do the same will be great in the Kingdom of Heaven» (Mt 5:19). Good example is the first element of the Christian Apostolate.