If ISIS made a Coin....
No exchange would trade it since it funds terrorism and depending on the country, the exchange could be shut down
Mining pools and people would attack the Coin
It's value would be 0
I don't think anyone would try to attack the coin (there would be no economic benefit from doing so). I think that no one would mine on it period, which would make it centralized, which take away from it's (already zero) value