In terms of the Kingdom of God, there are two "cities" that are of significance. The first city is Jerusalem. Jerusalem represents that which is brought about by God’s initiative. The second city is Babylon. Babylon represents that which is brought about by our initiative.
If I am not mistaken, most religious activity, including Christian religious activity, is brought about by our initiative, although we may apply the name of Jesus Christ to our efforts. This is Babylon, and it always will murder God’s saints, apostles, and prophets.