You should have said:
"Not all Muslims are extremists or terrorists, but virtually all terrorists are Muslim."
In the US many of the worst terrorist attacks have been by white US citizens not Muslims. Las Vegas, Sandy Hook, Oklahoma City, Aurora, Edmonton..
Extremists and zealots of ANY religion are dangerous and always have been. Lunatics will do crazy things in the name of their god.
9/11 was the largest terrorist attack on US soil and yes, they were islamic extremists, mostly from Saudi Arabia - Which brings up the question, why is Saudi Arabia conspicuously missing from the banned country list?
I'm NOT saying, as you seem to think, that everyone claiming to be Muslim is a "good" person, but not all of them are "bad" people either. Most, like the rest of us, are just folks with families trying to live their life.
The ability to be a piece of human garbage crosses all lines of race, religion and ethnicity.