John 17 is Jesus's High Priestly Prayer, offered before the cross and overheard by the disciples. It is the inner life of the Son of God made audible. In the midst of interceding for his disciples and for all who will believe through them, Jesus pauses to define eternal life — not as a duration but as a relationship. The definition is precise and stunning: eternal life is knowing God. Not knowing about God; knowing him — the only true God and Jesus Christ whom he sent.

From the writers we read together

C.S. Lewis

Oxford and Cambridge literary scholar, author of Mere Christianity (1898-1963)

Lewis came to faith through exactly the kind of knowing that John 17:3 describes — not by resolving all his intellectual objections first, but by beginning to know the Person whom the Gospels present. He described his conversion in Surprised by Joy as the reluctant recognition of Someone who had been pursuing him. His later reflection was that the knowledge of God is not primarily cerebral; it is the knowledge of a Presence — the same kind of knowing by which you know that a friend is in the room before you see their face.

Lewis's trilemma pressed the definition of eternal life in John 17:3 from the other direction: if this is not merely the Jesus of church tradition but the Son of God sent by the only true God, then knowing him is the most important knowing available to any human being. Not the most academically prestigious knowing, not the most economically useful knowing — the most important. Lewis's life after conversion was an exercise in the continuous ginōskō of John 17:3: the ongoing, deepening acquaintance with the Father and the Son that is, by definition, the eternal life available now.