How can David`s Lord be his Son? -> By the one Lord becoming the SonOfMan who is the Lord Jesus Christ.

For those who need three persons understand that our Lord is not bound by physical laws or carnal reasoning. -> Jesus is Son -> Jesus is the image of His Father -> Jesus and His Father are one -> Jesus was birthed by His HolySpirit -> The HolySpirit is Father -> The HolySpirit is the SpiritOfChrist Jesus -> Jesus birthed Himself by His HolySpirit -> Jesus raised Himself by His HolySpirit

This is true all at the same time so that Jesus is Lord, Father, Creator and Saviour. Jesus is the express image of the One Lord (who is Spirit) which the entire Bible speaks about.