Any word for group of individuals who have the same belief system?

Maybe you should do some research before calling people stupid, as you clearly don't understand what caucasian is. It has nothing to do with skin colour: https://en.wikipedia.org/wiki/Caucasian_race

And no, I probably couldn't name which country has the largest muslim population. If I had to guess, it would either be Pakistan or India. And even if I am wrong, what exactly is your point? Do you honestly believe the average person would know which country had the largest muslim population? 

Edit: Yes, I searched it up, and it was Indonesia. Don't act as if that is common knowledge, and I will admit I was a bit surprised to hear it.

For a moderator, you certainly have extremist thinking. Just because you say it's unislamic you must be doing it because of wanting to be pc. It can't be anything else surely. 

It must be related to Islam or descendants of Muslims (that may not even be Muslim), in other words, there has to be a way of blaming the religion or its followers (that is the logic which is implied by your statement, intentionally or unintentionally).

I don't think, but I know these attacks are not Islam related and not due to being pc, but being able to read, understand and being able to apply logic scientifically and justly regardless of culture, faith, color or lack of belief a group may have. 

Anyone who has studied Islamic history knows the difference between Muslims and Khawarij. Groups like ISIS are Khawarij not Muslim or part of any Islamic sect. According to islam itself, these people are non Muslim, they are reckless they are dangerous and they have caused huge bloodshed whenever they have cropped up. The ideology and actions clash with core beliefs of the faith or outwright ignore, contradict and or challenge them. In fact the groups with these ideologies have ended up killing Ali (the prophets cousin who was married to the prophets daughter, have slaughtered Muslims in mecca until the streets ran with blood and challenged the caliphate in mecca and when they lost declared the successor to the prophet a non Muslim and ordered for him to be killed as they didn't get their way). 

https://en.m.wikipedia.org/wiki/Khawarij

Secondly, applying science or logic to the situation will tell you it had nothing to do with pc.

The religion outlaws numerous things and these extremists you like to call Muslim, consistently and more than often than you know or think keep breaking,  defying, ignoring many sacred laws. 

So if by:

1) Islamic doctrine (hadith) they aren't Muslim;
2) through their actions they aren't Muslim; 
3) through practice they aren't Muslim;
4) aren't recognised as Muslims by over 99+% off the Muslim world including scholars;

Them by what logic does it make them Muslim and by what logic does than mean people are just being pc?!

People such as yourself make matters worse as you see Islam the same way as the extremists group do. Your understanding of the faith is not much different than those groups. Not only do you empower these idiotic groups by saying they are something they are not, you vilify every innocent party along the process. This attitude hasn't helped since 9/11 and the fact is it has made things worse. By empowering these people you aren't helping anyone but these extremist groups and giving them far more credibility than they even remotely deserve.

The fact that you have called people who may have a better understanding of these groups because of their knowledge on the subject worse than extremists themselves and worse than those who go on killing sprees shows ignorance, hatred, arrogance and it would be an attitude that would get other users banned for life. 

You mean like this Arabic ex-Muslim who has read the authentic Islamic texts and thoroughly researched the primary sources? To be quite blunt, your lengthy response was a waste and was more aimed towards making yourself appear to be the more "sane" person rather than actually being the more sane person. For goodness sakes, to summarize your reply in one sentence, you're literally arguing that Islam has nothing to do with Islam. Anyways, enjoy these two videos.

Trigger warning (and yes, an actual trigger warning): Skip to 1:06 if you want to skip the graphic introduction of the bottom two videos.

Here's the Arabic version in case you're curious:

Skip to 0:21 for these two videos:

And here's the Arabic version:

Just received the news aswell. He was planning his amok run.

So much credibility for cnn calling it an islamic terrorist attack.