I know this source isn't the best, but Urban Dictionary says the following:
"A militant atheist is one who is hostile towards religion. They differ from moderate atheists because they have the desire to propagate atheism and also hold religion to be harmful. Militant atheism was an integral part of the French Revolution, Soviet Union, Cultural Revolution, and is expresses itself today in the ideas of the New Atheist authors."
"A militant atheist is one who is hostile towards religion. They differ from moderate atheists because they have the desire to propagate atheism and also hold religion to be harmful. Militant atheism was an integral part of the French Revolution, Soviet Union, Cultural Revolution, and is expresses itself today in the ideas of the New Atheist authors."