“And this is the testimony: that God has given us eternal life, and this life is in His Son.”
and this life is in His Son
The Son is the means to eternal life. We can find eternal life nowhere else than in God’s beloved Son. There is no compromise here. This is because God’s Son is life (1:2; Jn 11:25; 14:6). Eternal life testifies to the Son’s life with the Father, a qualitative and eternal life. The possession of eternal life is a testimony to God’s Son. This is because eternal life fundamentally rests in Jesus Christ (Jn 1:4; 11:25; 14:6).
Note the sequence of John’s argument. The Father possesses eternal life and gave it to the humanity of Christ (Jn 5:26). So Jesus can say, “I live because of the Father” (Jn 6:57). In turn, Jesus gives believers eternal life (Jn 3:36; 5:24; 20:31). This is evidence that Jesus is the Son of God.
Jn 1: 4 “In Him was life, and the life was the light of men.”
Jn 5: 26 “For as the Father has life in Himself, so He has granted the Son to have life in Himself, 27 “and has given Him authority to execute judgment also, because He is the Son of Man.”
Jn 6: 57 “As the living Father sent Me, and I live because of the Father, so he who feeds on Me will live because of Me.”
Acts 3: 14 “But you denied the Holy One and the Just, and asked for a murderer to be granted to you, 15 “and killed the Prince of life, whom God raised from the dead, of which we are witnesses.”
Eternal life comes exclusively through Jesus Christ
The life of the Son of God both brings us into God’s presence in the eternal state and is a present possession. Jesus is the only way into God’s life and presence.
Jn 14: 6 “Jesus said to him, ‘I am the way, the truth, and the life. No one comes to the Father except through Me.’”