A Rational Fear of the Irrational
An irrational fear is being afraid of something when you have no reason to be apprehensive. If you have not read the Koran, then your fear of Islam could rightly be called irrational. If you have read the Koran, your apprehension is more than justified.
In Mein Kampf a man ranted about a superior race. In the Koran, a god makes the same type of claim to superiority for those who believe in Him exclusively and seek to impose His Will on those who don't.
A mortal's absurd i.e. irrational idea about race brought us the Holocaust. A god's thinking along the same line caused even more death and destruction; with a promise of much more to come.
Allah was initially comfortable with his followers only imposing His Will on those whom He calls idolaters, who had no choice but to submit or die.
61:9 It is He Who sent His Messenger forth with the guidance and the religion of truth, to make it triumph over every religion, even though the idolaters may be averse.
That all changed with the slaughter of the men of the Banu Qurayzah.
The massacre of a People of the Book was a game changer, not to make light of a pitiless deplorable act, and in effect made them candidates for conversion or slaughter in Allah's Cause, the Jizya notwithstanding, as confirmed by a subsequent revelation where Islam must be made to triumph over every religion, not just that of the idolaters.
48:28 It is He Who sent forth His Messenger with the guidance and the religion of truth, that He may exalt it above every other religion. Allah suffices as Witness.
Those who read Mein Kampf and, fearing the irrational, escaped to the Americas, survived. Those who didn't, died! Today, there is no escaping the irrational; you stand your ground, you fight and win, or you die.
Recommended: Jihad in the Koran.