The problem with Islam is that it lacks moderation. There are no restraints in place to curtail extremism. In fact the extremist represents the fundamentalist approach. From the beginning, Islam set its sights on world conquest through jihad. We should not be fooled into thinking that Islam and Western Liberal post-enlightenment values can coexist.
Everyone on the political left isn't obsessed with defending Islam but some are.
If I had to choose between living among Christians or Muslims, well I've done a bit of both and when religious nuts go wacko and kill here we generally prosecute them.
Harris and other scholars identify key verses in the Bible and Koran that have moderated Xtianity and likely energized violent Muslims.