Because it represents the whore of Babylon. But in my opinion it is not Catholic church/Vatican alone, but an evil world system in general, controlled by the Antichrist, during the last days before Jesus’ return. The whore of Babylon also has religious connotations: spiritual adultery with the beast being the focus of an ungodly, end-times religious system.
Talking about Catholic church: the Catholic Church/Vatican took the pagan philosophy and made it the buckler of faith against the heathen. Vatican took the pagan Roman Pantheon, temple of all the gods, and made it sacred to all the martyrs; so it stands to this day. Vatican took the pagan Sunday and made it the Christian Sunday. Vatican took the pagan Easter and made it the feast we celebrate during this season. The Sun was a foremost god with heathendom.
Did you know that Mary worship came from ancient Babylon where the virgin mother-goddess was worshiped under the name “Ishtar.” Elsewhere in the Near East, the mother-goddess was called Astarte, Ashtoreth, Persephone, Artemis, Diana of Ephesus, Venus, and Isis.“ This goddess, considered to be greater than any god, was called by these heathen the "virgin mother, merciful mother, Queen of Heaven, and my lady which is what "Madonna” means in Italian.
