Here’s a stupid question: why is the Catholic Church fair game BUT NON-CHRISTIAN RELIGIONS (you know who) ARE NOT ?
Muslims, until very recently, have largely been ignored in the US and have made very little contribution to our Western way of thinking. They have never been a part of the American establishment of institutions and are, therefore, not part of the liberal enemy camp.
If you want to go further back in history, you can also take into account that Western civilization has become a post-enlightenment culture which overvalues the scientific method and places undue skepticism on the role of "authority".