Muslims have existed for 1400 years, and yes, they've done some bad things, but they could never defeat Christianity or the West. Leftists have existed for 150 years, and they already defeated the West and Christianity. Which is the threat to fight? They try to distract us with Muslims. (Which by the way, once they are finished using them, they will destroy them even quicker.)
We'd be better off having a million Muslim and no leftists, than a 10,000 leftists and no Muslims.