Summary: Is Jesus making the Law binding upon Christians in these verses?
Neither Jot, nor Tittle
This text has many emphatic markers in the Greek which indicates that what Jesus says here is to be taken with all seriousness. We need to be reminded again that the Sermon on the Mount was preached to His disciples in the light of dividing the true disciples who hear the words of Jesus and put them into practice and those who are foolish and do not. The fact that this sermon had been passed down in Scripture to us today shows that Jesus is not just talking to the twelve or even the massed crowds, but to us as well. Seeing that this is the case, we need to pay heed to what is said.
Verse 17 begins with the imperative “Do not begin to say that I have come to destroy the law and the prophets.” This is followed by the strong Greek word for “but” followed by “to fulfill”. The Law and the Prophets were often put together to indicate the totality of Scripture. What Jesus is saying positively is that He came to completely fulfill the Scripture. Sometimes we tend to get bogged down into the commandments in the Law and take our eyes from the totality of the Scripture, which in that day was the Old Testament by itself
Jesus consistently taught that He came as the fulfillment of the Old Testament. In the Gospel of John, he tried to tell the Pharisees that it was their testimony of Jesus Himself which was the way to eternal life (John 5:39-40). After the resurrection, He opened the eyes of the Emmaus disciples to the testimony of Scripture concerning Himself and later in the appearance to the apostles that night. So this statement is more than just a statement that the Law of Moses was to be kept, and that Jesus expected this to be taught. It is rather a statement of the absolute inspiration and divine authority of the Scripture as a whole.
In verse 18, Jesus begins the verse with the strong word “Amen”. Amen is a word in Hebrew which has the meaning of “so let it be!” It is interesting that Jesus begins his important statements with either a single or double amen. The church, on the other hand, responds to the words of Jesus with “Amen”. The “so let it be” of Jesus “shall be.” By using the Amen, Jesus is equating His words to the divine authority and inspiration of Scripture. This is a strong claim to Jesus’ divinity when He puts His words at par with what is the God breathed word in Scripture.
Jesus also states in the verse a prophecy that at some time in the future, the heavens and the earth will pass away. But until that is fulfilled, not one Word or even a little letter like the Hebrew Yod will become irrelevant. Jesus is telling His true disciples that all of Scripture is to be revered and honored as His word.
In the church age, we have the divinely inspired New Testament which stands with the Old. Both are equally the Word of God and are to be understood as the product of the same Holy Spirit who inspired every word of Scripture. Unfortunately, much of the Old Testament has been dismissed as irrelevant by the church. In some circles, it is even seen as evil. But Jesus warns His true disciples that whosoever disregards even the slightest letter from the Word will become the slightest in the Kingdom. In other words, the one who lays aside a single Scripture will be laid aside in the Kingdom of Heaven. Those who declare Scripture to be irrelevant will be irrelevant to God’s Kingdom.