I take it that you have heard of the Battle of the Camel?Because invading peaceful nations contradict the quran in which it says
(2:190)
Fight in the way of Allah those who fight you but do not transgress. Indeed. Allah does not like transgressors.
Can you comprehend what the verse says to the Muslims?
Which side of it was not composed of Muslims?
How many of those were atheists?
Who is seriously proposing that ISIS are atheists?