Eternal life can be seen as a conscious existence in an ideal place with an ideal body without end. Jesus, at the beginning of His “high priestly” prayer in John 17, gives a different perspective.
“Father, the hour has come; glorify your Son that the Son may glorify you, 2 since you have given him authority over all flesh, to give eternal life to all whom you have given him. 3 And this is eternal life, that they know you, the only true God, and Jesus Christ whom you have sent.
John 17:1b-3 (ESV)
While Jesus would speak later about the “glory” He had with the Father before the world existed and His desire to return to that, the glory He speaks of here is His victory on the cross. Being crucified and forsaken by God is about as inglorious as it comes, but in Jesus’ situation He is doing it out of love for the Father and for us and for obedience to the Father’s plan. There is great glory in that.
Jesus will do this because He has been given “authority over all flesh”. Jesus has ultimate right to judge all humanity. That is part of His authority. But here it is the authority to give eternal life. He is in position to be the sacrifice for sin and thus bestow eternal life because: He is human, He has been sinless, and the Father has chose Him for the role. At the time of this prayer, Jesus is ready to get it done.
Verse 3 is an enlightening observation. To have eternal life is to know the Father and Jesus. Eternal life is not just eternal existence or consciousness. Those who find themselves in the final punishment of Hell will also exist and be conscious. You can’t call that “life”. That is eternal death because you are forsaken by God at that point. Life is being in connection and relationship with God. All good things come from God. Any joy of living comes when you have some degree of knowing God.
Are you alive in that sense when you are physically alive on Earth but don’t have any connection to God? The Bible would say no:
And you were dead in the trespasses and sins 2 in which you once walked,
Ephesians 2:1-2a (ESV)
In this situation we are still physically alive on Earth, we are not forsaken by God, but we do not “know” Him either. The same is true for those in Sheol. They are not forsaken yet, but clearly they are not living. They merely exist.
Life truly starts when Jesus “connects” us to himself. I use the word “connect” for lack of a better term. The connection is not a cognitive belief, because people who are too young or brain damaged can have this connection. It is not something that you can will for yourself. God gives it. For people of normal cognition, this happens when God breaks through whatever barrier exists in the human mind and/or soul or spirit and gives us a recognition that the story of Jesus is real and that the promise of God to give eternal life is true and that we now trust it. The next step is baptism, which is where Jesus promises to make this connection. At this point we are “in Christ”. We also “know” Him at this point. The actual mechanics of this at God’s level are not explained to us.
This life will carry over seamlessly through death and into a conscious existence in Heaven, unless we somehow separate ourselves from Jesus.
Heaven and the New Earth will be characterized by many joys which are all the creation of God. Chief among these joys is our ongoing and expanded interaction with God. It will be life to speak to Jesus face-to-face. It will be life to experience every way that the Holy Spirit and the Father manifest themselves in us and in our space.
As a Christian you are alive right now. Greater levels of life will be evident once we get rid of our sin-damaged flesh. That is something to look forward to.