Uh, instead of saying "some Muslims (not all)", why not identify that group of people by something else, rather than their religion?
Because "muslim" categorises a massive number of people with immensely wide characters/attributes/history/culture and is not at all representative of the people you're talking about.
Using the word "muslim" immediately makes you think of all muslims, regardless of your qualifier of "not all muslims".
There's more to define these particular people besides their faith, and when you have a faith which makes up 23% of the world population, it's just ridiculous to use that faith to identify a tiny population.