Revelation 17:4 - Matthew Poole's English Annotations on the Holy Bible

And the woman was arrayed in a purple and scarlet colour; purple was the colour of kings and princes: this woman, Revelation 18:7, said she was queen. Scarlet also was a rich and noble colour, anciently most used in a time of war. How much it is in use with the pope and his cardinals, is sufficiently known. And decked with gold and precious stones and pearls; this shows the worldly riches of the papacy. Having a golden cup in her hand full of abominations and filthiness of her fornication; alluring and tempting persons to idolatry, as whores use to do with their philters, or enchanted cups, allure and provoke men to sensual satisfactions.