When the above passage was written there was no RCC . IMO God was/is speaking of Judaism, not RCC.
Revelation 18 is prophecy concerning the fall and destruction of Babylon that great city - as the original city of Babylon was still in ruins and never dwelt in again it is certainly not referring to Babylon in Mesopotamia
As Babylon is the source of false religion that is similar to the stories and doctrines of Moses and the Hebrews, but nevertheless of different gods - so Rome is from the referred to in similar terms.
For Roman Catholicism is similar to the gospels and the doctrines of the NT but is of other gods. Even as a practicing Catholic I knew that what was written and what we did were two very different ways.
Rev 18 - read the chapter
2 And he called out with a mighty voice,
“Fallen, fallen is Babylon the great!
It has become a dwelling place of demons, a haunt of every foul spirit, a haunt of every foul and hateful bird;
3 For all nations have drunk the wine of her impure passion, and the kings of the earth have committed fornication with her, and the merchants of the earth have grown rich with the wealth of her wantonness.”
4 Then I heard another voice from heaven saying,
“Come out of her, my people, lest you take part in her sins, lest you share in her plagues; - (lots of Spirit-filled Christians who can pray in tongues remain with the RCC and still pray to Mary!!)
5 for her sins are heaped high as heaven, and God has remembered her iniquities.
9 And the kings of the earth, who committed fornication and were wanton with her,
will weep and wail over her when they see the smoke of her burning;
10 they will stand far off, in fear of her torment, and say, “Alas! alas! thou great city, thou mighty city, Babylon! In one hour has thy judgment come.”
23 and the light of a lamp shall shine in thee no more; and the voice of bridegroom and bride shall be heard in thee no more;
for thy merchants were the great men of the earth,
and all nations were deceived by thy sorcery.
24
And in her was found the blood of prophets and of saints, and of all who have been slain on earth.”
Very high probability that Rome will be nuked by Russia (the warning given at Fatima 1917)