Islam has both a theological and political ideology: a belief in Allah and a political ideology built around the Koran and the teachings of its founder Muhammad. Christianity (Christ), a Jew, teaches us to render unto Caesar what is Caesar's and to God (Allah) what is God's. This has allowed for a non-theocratic political tradition to develop in the West and in Israel. This, in tern, has led to the development of principles of civil and religious liberty.
Islam teaches even to reinterpret or much less to disagree with the Koran's 6000 verses, 114 chapters or Suras which deal with law, politics and faith is punishable by death. Islamic authorities also hold that parts of it written last have more authority and override those written earlier (theory of abrogation).
Specifically, they are parts of the Koran written after 622 A.D. These are Suras 9 and 5.
Sura 9, verse 5, reads: "Fight and slay the unbelievers wherever you find them, and lie in wait for them, in every stratagem of war. But if they repent, and establish regular prayers and practice regular charity, then open the way for them....
Sura 9, verse 29, states: "Fight those who believe not in Allah nor the Last Day, nor hold that forbidden which hath been forbidden by Allah and His Apostle, nor acknowledge the religion the religion of Truth, even if they are of the 40 people of the Book, until they pay the jizya (tax) with willing submission, and feel themselves subdued."
Sura 5, verse 51, reads: "Oh ye who believe! Take not the Jews and the Christians for your friends and protectors; they are but friends and protectors to each other. And he amongst you that turns to them for friendship is of them. Verily Allah guideth not the unjust."
And Sura 3, verse 28, introduces the doctrine of taqiyya, which holds that Muslims should not be friends with the infidel except as deception, always with the goal of converting, subduing, or destroying him."
Muslims who truly believe in the above are the individuals and groups that present a threat to Western Civilization.