In furtherance of the 'mark of the beast' discussion, it should be noted that the Roman numerals (1-500) are MCLXVI and equals 666 (support for the view that the 2nd beast of Revelation is a one world religious system).
Consider also that the Church of Pergamos (does Purgatory come to mind?) in Rev 2:12-13 is where (((Satan's))) seat is and where (((Satan))) dwelleth.
The Church of Pergamos had a hierarchal system similar to the RCC.