The prophecy concerning Babylon in Jeremiah chapters 50 and 51 have their fulfillment in Revelation. And the description of her judgment is seen in Revelation 17 and 18. That is the loud cry call to come out of Babylon. And I heard another voice from heaven, saying, come out of her my people, that ye receive not of her plaques.
Revelation sends a call of warning before judgment and that has been the pattern through the ages.
Genesis 6 and 7. In Lot s day the call was given to come out of Sodom and Gomorrah. Genesis 18 and 19. John the Baptist came out of the worldly society. While children of God remain in the world, we are not of the world.