Or have you forgotten the current (and centuries old) status of the Hagia Sophia and Temple Mount? We are constantly reminded of the Crusades, but no one (even in Austria) seems to remember the Siege of Vienna. Islamic imperialisms attempted continental pincer was a a major geopolitical issue in the Mediterranean into the Renaissance, and in the Balkans until, well, NOW.

Not that that invalidates your point; the Crusades were as much an alarmed response to that as they were any missionary undertaking. I just wanted to point out the phenomenon is not so one sided as some suggest. Several parallels are quite understandable; the desire for a new caliphate mirrors the old European desire for a new Holy Roman Empire (notwithstanding Voltaires infamous observation,) and just as unrealistic given that the longed for days of cultural and technological ascendance are long gone. There is a warning for the West in that, too; the Mideast has certainly not declined to the extent of Dark Age Europe, and look how things have progressed since.