I would advise that you don't question his faith in Christ without first conceptualizing certain biblical concepts like :

1. Was Jesus actually referring to his physical second appearance as He did??
   What if He meant the PRINCIPLES which will dominate the world instead of the subsisting human principles??
2. Have we actually conceptualize what Paul meant by Spiritual human bodies as different from physical bodies of flesh and blood which can't inherit eternity.
3. Where is the location of God's Kingdom? Isn't it supposed to be inside of us in our " hearts"?
4. Can a physical person inhabit our fleshy heart??
5. Was Jesus actually speaking about physical kingdom as the bonded Jews were expecting?

Nevertheless, we should never forget Paul's injection of restricting Revelations according to believers' levels of faith, because it can only be unto us according to our level of faith!!

Shalom!