In prayer to his Father, Jesus said: “This is eternal life, that they may know you, the only true God, and Jesus Christ whom you have sent.” (John 17:3, NRSV) These words reveal that eternal life is not simply to be equated with everlasting or endless existence, merely an unending prolongation of life. The distinctive quality of this life is an abiding relationship with God and his beloved Son, hence something far grander and richer than simply an endless existence.
Thus, in commenting on John 17:3, The Expositor’s Bible Commentary states:
The second sentence defines the nature of eternal life. It is not described in chronological terms but by a relationship. Life is active involvement with environment. . . . whether it be physical or personal. The highest kind of life is involvement with the highest kind of environment. For the complete fulfillment of our being, we must know God. This, said Jesus, constitutes eternal life. Not only is it endless, since the knowledge of God would require an eternity to develop fully, but qualitatively it must exist in an eternal dimension.
Our knowing the Father as the only true God includes being exclusively devoted to him, loving him, striving to do what is pleasing in his sight, believing in his deep love and tender care for us even when facing severe trials, trusting him and his word, and looking to him for help, guidance, and comfort. (Proverbs 3:5, 6; 30:5, 6; Matthew 4:10; 22:37; 2 Corinthians 1:3, 4; Hebrews 12:7-10; 13:5, 6; James 1:5; 1 Peter 4:1, 2; 5:7) “God is love,” for “love” sums up all that he is in his very being. Therefore, to know him means to be loving as he is loving, compassionate as he is compassionate, and forgiving as he is forgiving. (Matthew 18:21-35; Luke 6:36; James 2:13; l John 4:16, 20, 21) Those who treat any of God’s human children in a hateful, cruel, or contemptuous manner do not know him. Such persons may have intellectual knowledge about God which they have acquired from reading the Holy Scriptures, but they do not have a relationship with him. The Father is unknown to them, and he does not recognize them as his children. To Christians, the apostle John writes:
Beloved let us love one another, because love is from God; everyone who loves is born of God and knows God. Whoever does not love does not know God, for God is love.—1 John 4:7, 8; NRSV.
Knowing the Father in the sense of having a relationship with him is impossible, however, without also knowing Jesus Christ as the one whom the Father sent into the world of mankind so that our sins might be forgiven on the basis of faith in the efficacy of his Son’s sacrificial death. (John 3:16-18; 5:36-40; 6:29; 7:28, 29; 10:36; 11:42; 17:8, 20-26; 1 John 2:1-5; 3:23) Again, John writes:
The way we came to know love was that he laid down his life for us; so we ought to lay down our lives for our brothers.—1 John 3:16, NAB.
Without the Son we could not truly come to know the God of love. Jesus perfectly reflected his Father’s love and delighted in always doing his Father’s will. (John 8:29; 15:9-13) Therefore, to reject the Son would constitute a rejection of the Father. As Jesus Christ said to certain men who refused to believe in him and sought to kill him: “If God were your Father, you would love me, for I came from God and am here; I did not come on my own, but he sent me.” (John 8:42, NAB) On the other hand, all who recognize Jesus as having been sent by the Father and have faith in him as the Son of God who laid down his life for them, instead of remaining condemned sinners with death in view, come into possession of a new life as beloved children of God and brothers of Christ. (Matthew 25:31-45; Hebrews 2:10-18; 1 John 3:1) The outward manifestation of their faith is a life that harmonizes with the example and teaching of God’s Son and thus demonstrates that they indeed know him. (Matthew 7:21-25; Luke 6:46; John 13:13-17, 34, 35; Romans 15:1-6; 1 Peter 2:20-24; 1 John 2:6).
Since it is possible for humans to have an approved relationship with the Father and his Son on the basis of their faith in Christ, eternal life is spoken of in the Scriptures as a present possession. The following words are addressed to believers: “God gave us eternal life, and this life is in his Son. Whoever possesses the Son has life; whoever does not possess the Son of God does not have life. I write these things to you so that you may know that you have eternal life, you who believe in the name of the Son of God.” (1 John 5:11-13, NAB).
Eternal life in all its fullness, though, will not be enjoyed by believers until they find themselves in the sinless state, with their bodies transformed to be like the glorious body of God’s Son. (Philippians 3:20, 21; 1 John 3:2, 3) At that time, they will perfectly reflect the love of the Father and of the Son. They will then in the truest sense know God and his Son, and that marvelous relationship of being approved children of God and brothers of Christ will continue for all eternity. Jesus provided this assurance to those who were willing to abandon everything to be his loyal followers: “Truly I tell you: there is no one who has given up home, brothers or sisters, mother, father or children, or land, for my sake and for the gospel, who will not receive in this age a hundred times as much—houses, brothers and sisters, mothers and children, and land—and persecutions besides; and in the age to come eternal life.” (Mark 10:29-31, REB).