Revelation 17:1,2

An angel comes to John and proposes to show him the judgment of the great whore that sitteth on many waters. In chapter sixteen we had the vials poured out and all the striking symbolism of the judgment that was to fall; and now the angel says he will explain it more fully. He calls the object of this judgment a whore that sitteth upon many waters. The whore is afterwards shown to be a city and the many waters are peoples and nations and tongues. It is here said that "the inhabitants of the earth have been made drunk with the wine of her fornication." Her idolatry had permeated the world. The Old Testament had used the words adultery and fornication to describe idolatry. Some have thought that these words were used only when Israel, God's covenant people, were guilty of defection and fell into idolatry, and therefore they couldn't be applied to pagan Rome. But these words in the Old Testament are applied to other nations such as Babylon and Nineveh, and may here apply to pagan Rome for papal Rome has not come into vision.