What does ISIS mean when they issue repeated threats about conquering Rome? This is not, as some have speculated, a metaphorical term for America. It is not directed at some vague notion of Christianity. It is not about a larger invasion of the West.
They mean this:
To those who know, who understand the longstanding conflict that has spanned over a millennium, the reason is clear. What is represented in this image – published several months ago on the cover of the official magazine of the Islamic State – is the only thing that matters: the seat of Christendom itself, the See of Peter, the Vicar of Christ.
We can’t afford to forget this. They won’t.