Why was it important that David was related to Jesus?

Answer 1

Another answer from our community:

Because it was fulfillment of prophecy(Genesis 22:17, 18) It would be an identifying mark of the Messiah when he came(Matthew 1:1-16)(Luke 3:23,31,34), and would give him the legal (Acts 2:29-31)and physical right to the throne of Israel and rulership of the earth.

A little history:

Immediately after the sin of Adam in the Garden of Eden, God spoke the first prophecy in The Bible at Genesis 3:15. Satan's wickedness and Adam's selfishness had brought sin and death to the human family,(Romans 5:12) so God promised a redeemer would come to correct the situation and destroy satan, eventually restoring God's original purpose for mankind and the earth.(Isaiah 55:11, 45:18)(Acts 17:26)

This Messiah would be equal to Adam, in that he would be a perfect man, but unlike Adam, would be faithful to God, his father, in all things, providing an atoning sacrifice(1 John 2:2), effectively replacing Adam as our 'father' thus giving people a choice as to who's example to follow. (1 Corinthians 15:45)

Years later, the faithful man Abraham, was called "God's friend"(James 2:23). Because he was such a loyal worshiper, God promised that the lineage of the Christ would continue through his descendants. David was one of these descendants, and God loved him. Though he made some really bad mistakes, he sincerely repented and remained loyal to his God.

When the Jesus arrived (exactly on time prophetically-Daniel 9:25) he was, as prophesied, 'born of a virgin'(Isaiah 7:14)(Matthew 1:18-23),in the line of David and Abraham (through both his parents), in Bethlehem(Micah 5:2), and fulfilling many, many other messianic prophecies, proving that he was infact, the prophesied Messiah who would save the world.(Luke 2:10, 11, 1 John 4:14)

Answer 2

The first century Jews believed that their longed-for Messiah would be a descendant of King David, so if Jesus was not said to have been in this line of descent the Jews could easily have denied that he was the Christ, the Messiah.

To demonstrate the lineage of Jesus, the Gospels of both Matthew and Luke provided genealogies back through Joseph to David: Matthew through Joseph's father Jacob and Lukethrough Joseph's father Heli. Raymond E. Brown (An Introduction to the New Testament) says there are many differences in Matthew's and Luke's genealogies, and those who think of Luke as having tradition stemming from Mary have tried to argue that his is the true family genealogy of Jesus or even to reconcile the two genealogies. He says there is little likelihood that either is strictly historical.

The Catholic Church has always accepted that in Luke's Gospel Heli was father of Joseph and adhered to a tradition that Joachim was the father of Mary, but many Protestants insist that Heli was Mary's father, in spite of Luke 3:23.