Those people are defending non-extremist Muslims, not all Islam. There's a huge difference, though I don't expect you to grasp it based on the general level of ignorance you've displayed thus far.
They're not defending their beliefs, they're defending their right to exist. It's the same thing they do for Christians and Jews and Buddhists etc etc etc.
It’s interesting that they don’t extend the logic to, say, Nazis. I am Personally consistent on this: both Muslims and Nazis should have the right to exist, but not to force their views on others.
I've never met a Muslim that wanted to kill three quarters of society, but that's the only kind of Nazi you could ever possibly meet. It's kind of their only thing. Tolerance of intolerance only leads to more intolerance. It's why people who are lactose-intolerant should avoid lactose. Society is, by nature, Nazi-intolerant, Nazis make society shit itself.
I'm not a Muslim apologist. I am not a fan of religion in general and Islam in particular. I've been downvoted to hell for being against Hamas and Hazbollah. So, nah, I'm pretty consistent.
The problem is religious fanaticism. It doesn't matter what the flavor of your extreme fundamentalist religion, the cyanide Koolaid it represents will kill you. Don't think for a minute that extreme fundamentalist Christians wouldn't do similar stuff.