A comment by Livius from the link, with which i agree:
“Islamic terrorism comes from Islam, and has been a feature of the cult since the beginning.
Both Russia and the US were stupid enough to think they could use this against each other during the Cold War.
Both of them had obviously forgotten that the way the Muslims got to overrun Spain in the 8th century, shortly after the foundation of the cult, was that they had been INVITED in by a king who was warring on another king and thought he could use them to attack his enemy. They did attack his enemy - after killing the first king himself, of course - and then went on to attack all of Spain.
This is playing out just the same way.”
Don’t forget that was also how the Arabs took SIcily and Malta-when a rebellious Byzantine admiral Euphemius solicited their help against the Byzantine King Michael II, and that was also how the Ottoman Turks got a foothold within the Byzantine Empire later when the regent John VI Kantakouzenos solicited the aid of Sultan and Bey Orhan Ghazi against the then queen dowager and then the legitimate King John V.