Eternal life is God's free gift to us through His Son Jesus Christ. It is life as God has life.
John 17:3 gives us the definition of eternal life: to know the one true God and His Son whom He sent.
This life is for everyone who will repent and believe in Jesus.
This life of abundance begins at the moment of our surrender to Jesus. Just as Adam and Eve walked with God in the Garden, in intimacy and love, this relationship is now restored to us. We will grow in this process of becoming more like Jesus and enjoying His love.
This life is the Father and Son abiding in us.