Is heaven and the Kingdom of God that Jesus talks about in his ministry the same thing? What, then, is the New Jerusalem? Or are all those one and the same thing?
Yes, in certain ways they’re aspects of the same reality: the triumph of God’s grace in us. That’s really the best interpretation of what Jesus meant by “the Kingdom of God” or “the Kingdom of Heaven”: he could say “the Kingdom of God is among you” (Luke 17:21) because it isn’t really like any other kingdom we know of.
That’s why we pray “thy kingdom come” in the Lord’s Prayer: that his reign in us and in all women and men be made complete forever. In part because that’s what Heaven is: the fullness of life in and with God, forever, in which the triumph of love is so definitive that it can never be lost or corroded. It’s Heaven that is referred to as the New Jerusalem: the original Holy City was the place in which God chose to dwell among us in his Temple on Mount Zion.
Once Jerusalem was overthrown by the pagan Romans and the Temple was definitively destroyed in 70 AD, St. John could call Heaven a “New Jerusalem” in the Book of Revelation in a new and poignant way — referring to an eternal presence of God with men that could never suffer the same fate. And somehow the mystery is that we’re all part of this: Christ desires to triumph in all of our hearts and to have us close to him forever in Heaven!
Really hoping to make it there, where there will be no more "anon" and we will know exactly as we are known, in all charity! God bless you.
- Father Shane