The Son of David

“[Jesus] said to them, ‘How is it then that David, speaking by the Spirit, calls [Christ] ‘Lord’? For he says, ‘The Lord said to my Lord: sit at My right hand until I put Your enemies under Your feet.’ If then David calls Him ‘Lord’, how can He be his son?’” Matthew 22:44-45
In Matthew 22, Jesus is asked a series of questions by the Pharisees and Sadducees, not because they wanted to learn from Him, but because they wanted to trap Him in what He said (Matt. 22:15). But He silences all of them with His answers. Having done so, He then poses a tricky question to them. He asks them, whose son is the Christ? They answer, the son of David. Then He quotes to them Psalm 110:1 – “The Lord said to my Lord, sit at My right hand until I put Your enemies under Your feet.”
In the Jewish culture, a person’s ancestors were all greater than their descendants. Everyone had respect for their elders, and titles of respect were never bestowed on younger people by older people. Thus how can David as the ‘father’ of Christ, call Him ‘Lord’?
The Pharisees were unable to answer, but the answer is quite simple. Yes, Jesus was a descendant of David physically (through Mary) and legally (through Joseph). But He existed prior to His incarnation – and prior to David. He was the one who brought David himself into existence.