Being Jewish, Matthew spoke to the traditions of the Jewish faith. He knew in order to convince Jews of the Messianic nature of Christ, he would need to tie Jesus’ story to the OT in which the Jewish studied and understood.
Matthew used many references from the Old Testament Scriptures in his portrayal of Jesus as being the fulfillment to the prophecies of the long awaited Messiah. He spends a considerable amount of writing on this principle to get the Jewish nation of Israel to understand and accept Jesus as their Messiah. It was to the nation of Israel that Jesus came as a fulfillment of God’s promise of a king from the line of David. Matthew proves that point in his genealogy tracing Jesus back to David. For the Jews, even though the Messiah would be more than just a physical king, Matthew connects the dots to that promise.
Matthew used scripture to show Jesus was the promised Messiah. He used the scripture which, the people written to, should have easily pointed them to Jesus as the Christ. He wanted them to know so they would have every opportunity to turn and repent and be saved.
In the book of Matthew, Jesus is tied to the bloodline expected by the Jews who are the intended audience for this gospel. In light of this Jewish audience, Jesus’s identity as the fulfillment of the prophecies of the old testament (the long-awaited messiah) is important for Matthew to communicate clearly. For the Jewish community, establishing that Jesus’s story is the continuation of the Old Testament narrative is equivalent to proving that he is the foretold Messiah.
Right away, Matthew begins with the genealogy of Christ by focusing on connecting it to the old testament; specifically, he expresses the connection he has to Abraham and David and then goes on to describe him in chapter 1 of his book as Immanuel, “God with us.” This is so vital in demonstrating the fulfillment of Isaiah’s prophecy. I believe Matthew goes about it this way because of the fact that he wants to appeal to a Jewish mind set by demonstrating how the prophecy is fulfilled. If the Jewish people can’t see the evidence of the fulfilled prophecy, they can not see Christ as the true Messiah.
Matthew and Luke both introduce their gospels with the genealogy of Christ, but for different purposes. Matthew is concerned with Jesus’ earthly father, Joseph and his lineage, in an effort to link Jesus with the Old Testament prophecies and prove the fulfillment of the Old Testament prophecies as the Messiah. He refers to Hosea’s prophecy “ Out of Egypt I called my son.” (Hos.11:1), Isaiah’s prophecy of a prophet to lead the way of the Messiah (Is. 40:Matt. 3:3). This is important because Matthew attempts to prove that Jesus was exactly who he proclaimed to be, the Christ.