Rainsford it isn't that all Muslims are the same, or that anyone thinks that.
It's that the percentage of crazy, violent, murderous fundamentalists in Islam is way, WAY higher than in Christianity or Judaism. And there is more bleed over of that sort of mentality even into those who aren't that way. It is a less distinct line between the crazies and non-crazies than in those other two religions.
in Christianity, for example, in 2012 the real fundamentalist crazies are ostracized by the entire society, including the vast majority of their own religion. One thing that helps this is the vast number of sects within Christianity. All these sects help Christians avoid feeling too monolithic or too much solidarity, which can be dangerous in a crazy, false ideology based on bronze age, warlike, anti-woman myth.
So if you get an abortion clinic bomber or a Fred Phelps or what have you, these people might have a small group or following... but it never seems to get much traction and certainly doesn't ever seem to threaten to subsume Christianity or a large share of it.
The thing with Islam is that the crazies, the violent murderous intolerant anti-woman thugs... are not so easily isolated. Islam only has 2 or 3 sects... there are a few variants like Wahhabism etc, but overall... Islam is much, much more monolithic than the other two Abrahamic traditions are currently.
There is a much higher general approval of the crazies and their behavior among the MAJORITY of Muslims, even those who wouldn't directly participate in such actions.
You have the die hard, crazy ass Bin Laden types who are prepared to dedicate their life to murderous terrorism... this group is FAR larger than in the other two religions. This group enjoys MUCH higher approval among the rest of Islam than the equivalent groups do in the other two religions.
You then have the hordes of less extreme but still very dangerous, violent Muslims who might conduct themselves fairly normally on most days... but given the slightest reason to join into a mob and storm an embassy, rape a reporter, drag a Coptic Christian to their death... whatever, they're down. They are completely ready and willing to put their individuality and normal life aside at a moment's notice to get in on that sort of behavior. This group likewise is far far larger than in the other two religions. It's not even clear that such a group exists in the other two.
The percentage of truly civilized, decent Muslims who are completely compatible with the modern, western notions of civilization and human rights, is disturbingly small. They exist, and usually they exist because of isolated, prolonged exposure to western environments... but yes there are some in the middle eastern countries, etc too. No doubt. These are fine people and worthy of including in our civilization. I have no problem with them.
The problem is the percentages and the bleed over. So nobody is saying all Muslims are the same, we're saying there aren't enough modern, moderate Muslims. The percentage of crazy to non-crazy in Islam vs. Christianity is almost an exact flip. It's not quite that bad, but it's close. Christianity is a bunch of moderates with a handful of crazies, Islam is a bunch of crazies with a handful of moderates.