While their beliefs are somewhat correct (trying to convince other religion to follow islam) they're are doing it in the worst and most disgusting way possible. This may be okay in the old days but now there are much easier and more humane ways to express your message.
Tl;dr ISIS are doing this with correct reasons but implementing it in the worst and gruesome way possible. I agree with what Obama and others are doing, just as long as the innocent civilians are safe and will continue their life with no issues.
