One God and one Lord
See Ephesians 4:5-6 and 1 Timothy 2:5 where we also see the one God identified as the Father, and the Lord Jesus Christ identified as another, the one Lord and the one mediator. The best textual evidence also supports Jesus being the “only Master and Lord” of Jude 1:4, and the Father being “the only God” of Jude 1:25.
Paul is drawing on several OT verses prophesying about God’s people having two rulers, the Lord God, and underneath Him, the Lord’s servant David (the Messiah): Jeremiah 30:9, Ezekiel 34:23-24, Ezekiel 37:23-24, Hosea 3:4-5. These verses show that the Messiah takes the place of David as the highest ruler over God’s people, second only to the Lord God; He is the king and prince amongst God’s people. Indeed, the Messiah is the fulfilment of God’s promise that David would forever have a king on his throne.
Consequently, the meaning of the word ‘Lord’ (kurios) in 1 Corinthians 8:6 is king, just as David was called “my lord the king” (kurios in the Greek translations) alongside the Lord (kurios in the Greek translations) in 2 Samuel 15:21. Psalm 110:1 also refers to the Messiah as “my Lord” (kurios in Greek, adon in Hebrew) at the right hand of the Lord where He rules over His enemies and serves as a priest (the mediator between God and men, 1 Timothy 2:5). Psalm 2 shows the Messiah as the Lord’s anointed king who rules on His behalf.
1 Corinthians 8:6English Standard Version
yet for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist.