"I think that the hope that Islam can only be fixed from within, if I'm understandint that, is well intentioned but unrealistic"

Robomatic.....You sound as if you think we have a range of options.
In fact we have no alternative but to step "back from the brink".
Waging war on a country for dubious reasons is a certain way to radicalise the citizens of that country.

Perhaps Islam cannot be fixed, and as I've stated already, if that is indeed the case then we are already defeated.
I prefer to be optimistic and the example you cite of the Muslim/Muslim killings can sow the seeds of change among even radicalised Muslims.

We must change our foreign policy, and remove our invasion forces before any change can even start.

If we cannot change our unsustainable lifestyle and rapacious economic system....historically the main cause of conflict in the Middle East, then we must except the consequences...Ake