Your Bible says King David was God's Christ

What they don't tell you in Trinity world. The ancient King of Israel was God's Christ/Messiah, God's Anointed One. And because God promised David that his descendant would sit on the Davidic throne, the first century Jews expected the Christ/Messiah to be God's Christ, God's King of Israel, God's son, just as David and Solomon were those things. The Davidic King sat on the throne of Yahweh because he executed God's Kingly authority over Israel, the authority of that throne. God was their true King but Israel wanted a human King and so God anointed these human beings to be King over His people in His place. So it is with Jesus, King of the Jews, God's Christ. "I will be a Father to him and he will be a son to Me."

For Israel, there was one God, Yahweh, and one Lord, King David. See 1 Kings 1:36 LXX and compare 1 Corinthians 8:6. For this reason, Israel bowed down and worshiped Yahweh and the King (1 Chronicles 29:20,23).

David King = God's Messiah = God's Christ = God's Anointed
The Israelite King as Messiah: 1 Samuel 2:10; 16:3, 12-13; 2 Samuel 2:4,7; 3:39; 5:3,17; 12:7; 19:21; 22:51; 23:1; Psalm 2:2; 28:8; 45:7; 89:20; 132:17. Concerning Solomon, see 1 Kings 1:39, 45; 5:1; 2 Chronicles 6:42. See the same verses in the LXX (Christos/Christ).

This video is a brief overview. There is much more to be said concerning this topic.