The one and only true God. The name has everything in it – the only true God. The question of whether there is another God is irrelevant. There is only one God, God and Father. The Father of Jesus Christ is the true God.
“This is eternal life, that they may know you, the only true God, and Jesus Christ whom you have sent.” (John 17: 3)
“For we have one God, the Father, and one Lord, Jesus Christ.” -1 Corinthians 8: 6
The Father is the only true God, and Jesus Christ is Lord.