what does "militant activist" mean?
An "activist" is someone who supports a cause of some sort. It could be someone who collects money for AIDS education, petitions Congress for more AIDS educational programs and stages fund-raising events for AIDS charities.
A "militant activist" is someone who is often insistent and overbearing when it comes to supporting a cause. They often don't cooperate with existing groups and prefer to stage protests and use extreme methods to get their message heard.