What does Mark 12:35 mean?
Matthew adds more detail to this incident. Jesus asks the gathered Pharisees who they think is the father of the Christ. They respond that the Messiah is the son of David (Matthew 22:41–42). The Messiah wasn't referred to directly as the "son of David" until the mid-first century BC in writings by scribes. Like in Mark 9:11–13, Jesus doesn't contradict this scribal teaching but explains more fully what it means. He compares it to Psalm 110:1 (Mark 12:36) and shows how two seemingly contradictory statements can both be true.In Judaism, the ancestor "outranks" and represents all his descendants. This is shown in the argument that the priesthood of Melchizedek is pre-eminent over the priesthood of the Levites because Abraham, great-grandfather to Levi, tithed to Melchizedek (Hebrews 7:1–10). It would follow, then, that the Messiah, who would be the descendant of King David, would be subordinate to David (1 Chronicles 17:11–14; Jeremiah 23:5–6). So, tradition would state that while the Messiah would be a significant figure, rescuing Israel from her Gentile oppressors, he would be a man no more special than David.
The Bible uses the term "son of" in a couple of different ways. First, it can mean a male descendant of any generation. Jesus fulfills this requirement both through Joseph's genealogy (Matthew 1:6–16) and Mary's (Luke 3:23–31). "Son of" can also mean someone who exemplifies another's character. Jesus called the scribes and Pharisees sons of Satan because they tried to find a way to kill Jesus rather than recognizing He spoke the truth from God (John 8:39–47). The Messiah will be the "son" of David in this exemplary way because he will be king of a united Israel and will rule justly with a mind to God's heart.
Whether a biological descendant or one who images the character of another, David's "son" could not also be his "Lord" (Mark 12:36). Jesus wants to prove that the Messiah is more than just David's son. He can't be defined merely as a successor to David. In fact, He is David's Lord.