We are looking at the second phase of the Pagan Invasion into the Roman church, typified by the "church of Thyatira" and Jezebel's teachings. Idolatry, sexual immorality and other doctrinal perversions prevailed during the Middle-Ages / the Dark-Ages of church history. Thyatira was prophetically spot-on in describing what would happen to the Roman Catholic church during this time period, exactly. To find out more, please listen online and download the PowerPoint and extensive notes.
Link to Pope Gregory (the First)'s Letter to the Archbishop of Canterbury: http://www.britannia.com/history/docs/mellitus.html