This is eternal life, that they should know you, the only true God. The 17th chapter of the Gospel according to John is entitled “The Prayer of Jesus.”  It is a prayer that Jesus says for, and over the disciples as he neared his passion and death. In it, Jesus prays for his disciples even as he commends them to the Father for protection from the fallout that was sure to follow his death. In the prayer, Jesus also requests for them eternal life from the Father. What is this eternal life which Jesus was requesting for his disciples? Was he asking the Father to keep them alive for eternity? Or was he asking the Father to ensure that his disciples are granted free passage to heaven after their bodily deaths?
Oftentimes we tend to equate eternal life with life after death. By doing so, we make eternal life something that is removed from our present state (and superior to it) so much so that we somehow look forward to, or have a longing for it at the expense of the present one. Such would be very a simplistic way, if not also erroneous, of understanding eternal life. For eternal life is life itself. It is real life, not something removed from our present state and for which we look forward with eager expectation. Eternal life is the life that God had planned for creation right from the very beginning. It is a life whose beginning is found in this present, temporal and transient world, even as it extends beyond it. In simple terms, eternal life is a life with God. 
Jesus prays to the Father that those who belong to him, those whom the Father has given him, might be granted eternal life. To put it another way, he prays that the Father might give them the graces that would transform their lives from mere instances of existence into real life, lives with a purpose, full and happy lives. Jesus asks for graces on their behalf because such a life can only be gained through a recognition of, and union with God: “that they should know you, Father, and me too.” 
Whereas knowledge of God is the essence of eternal life, being with God is its culmination. In other words, the knowledge of God comes to full cycle in Jesus Christ, for Jesus Christ is the fullest revelation of the Father. One expresses his/her knowledge of God in his/her believing in Jesus Christ as the one whom the Father has sent to give us life. The request for eternal life on his disciples’ behalf is Jesus’ appeal to the Father that the disciples remain steadfast in their faith, for only in this is found eternal life. Only by remaining attached to Jesus their master through faith will the disciples be able to faithfully carry out Jesus’ mandate of proclaiming the good news to the ends of the earth. 
Pope Benedict XVI, Jesus of Nazareth