And this is the record, that God hath given to us eternal life, and this life is in his Son.
Hath given - aorist, 'gave,' once for all. Not only 'promised' it.
Life is in his Son - essentially (John 1:4; John 11:25; John 14:6); bodily (Colossians 2:9); operatively (2 Timothy 1:10) (Lange). It is in the second Adam, the Son of God, that this life is secured to us, which, if left to depend on us, we should lose, like the first Adam.