that they may all be one, just as you, Father, are in me, and I in you, that they also may be in us, so that the world may believe that you have sent me.Gospel of John 17:20
Consider the quote above from Jesus, then consider the transitive property of mathematics: if A = B and B = C, then A = C.
So if Jesus is one with God, and the disciples are one with Jesus, then the disciples are (or could be) one with God.
Thus, Jesus is praying that the disciples can be one with God as he is. Keeping in mind my basic premise that Jesus was imbibed with the Holy Spirit (aka had a mystical experience) at the time of his baptism, he is here seen hoping that the same thing will happen for the disciples when he is gone.
There are many such clues in early Christian literature that support this understanding of life of Jesus. It takes stepping away from the dogma that has been promulgated for 2000 years to see the true gospel (aka, good news).
TAKE AWAY: Is it time to start believing Jesus instead of believing in him?