QUESTIONS AND ANSWERS ABOUT JOHN 17:3: NOW THIS IS ETERNAL LIFE: THAT THEY KNOW YOU, THE ONLY TRUE GOD, AND JESUS CHRIST, WHOM YOU HAVE SENT.

John 17:1-3
After Jesus said this, he looked toward heaven and prayed: “Father, the hour has come. Glorify your Son, that your Son may glorify you. For you granted him authority over all people that he might give eternal life to all those you have given him. Now this is eternal life: that they know you, the only true God, and Jesus Christ, whom you have sent.”

If Jesus is one of the Trinity, why does he say the Father is the only true God?

The aforementioned Scripture is one of the anti-Trinitarians’ battle horses against the divinity of Jesus Christ. Verse 3 argues that the Father is the only true God, while Jesus Christ is his sent. Is it therefore necessary to deny the divinity of Jesus Christ, by which he is of the same substance as the Father? Absolutely no. Jesus Christ is God as his Father (John 1:1-3.14; 8:58; Colossians 1:16-17; Titus 2:13; 2 Peter 1:1; Revelation 1:17-18; 22:6.16), but he is not a second God, since he participates fully in the same divine nature of the Father (John 16:15), being one with him (John 10:30). Therefore the Spirit of God is, at the same time, the Spirit of the Father (Matthew 10:20) and the Spirit of Jesus (Acts 16:6-7; Galatians 4:6; Philippians 1:19; 1 Peter 1:10-12). What was to be glorified of Jesus is the human nature that the divine Second Person of the Trinity united with himself hypostatically, becoming man (John 1:14; Galatians 4:4) while remaining God (John 20:28; Acts 20:28; Colossians 2:9). Paul speaks of this glorification in his letter to the Philippians: “In your relationships with one another, have the same mindset as Christ Jesus: Who, being in very nature God, did not consider equality with God something to be used to his own advantage; rather, he made himself nothing by taking the very nature of a servant, being made in human likeness. And being found in appearance as a man, he humbled himself by becoming obedient to death—even death on a cross! Therefore God exalted him to the highest place and gave him the name that is above every name, that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue acknowledge that Jesus Christ is Lord, to the glory of God the Father.” (Philippians 2:5-11) It must be concluded that the words of Jesus: “Now this is eternal life: that they know you, the only true God, and Jesus Christ, whom you have sent” (John 17:3), refer to his human nature. At the same time, as a divine Person he is the only true God with the Father.