There are many reasons. I can't sum it upujG in one line. The main reason is humans don't base their actions/positions/lifestyles off of religion. Just look at politics and how cruel it is. There is so much injustice because Christians, Jews, Hindus and Muslims are liars when they claim to have ethical approach to worldly matters. I'm very political orientated person, it's my passion. However I refuse to enter professional field of politics because that would require me to abandon my ethics and take unjust positions even though my God tells me to never sell my soul even at any cost. I actually was that person who refused to sell my soul. And that's why I often sympathized with non state actors train of though(not political actions). Until I realized that ethics, morals, justice and God are very hated by the adherents of these faiths. That was the main reason, I realized that society and lifestyle isn't guided by principles of religion. Which also means nobody actually believes in God since they clearly don't emulate him or his messengers.
The reason I use AQ/ISIS example so much is because they are unintended consquence of the lies majority of religious adherents spread. Let's look at AQ/ISIS train of thought. They believe everyone around them is very hostile to religion. They see people around them including their own faith don't want to implement religion. They know that the people around them are atheists that are guided by secular/capitalistic train of thought and not by religion. This is why they resort to violence in their ideological struggle with the worlds inhabitants. We dont have to agree with ISIS/AQ actions. But we need to study their train of thought if we want to understand why they're a reality , and a growing one too.
So leave the violence stuff aside, as far as violence goes. They don't even make top 10 in the scales. I'm not a bigot or bias person. So I won't view them as most evil people just for them being Muslim. I estimate/judge what's evil based on actions. Capitalism has caused lots more suffering than AQ/ISIS could ever be able to inflict.
What I want to focus on is ideological aspect. Most adherents of religion won't let religion dictate their personal decisions or lifestye. Shouldn't this tell you something? It means they take logical and sometimes unethical/immoral(according to abrahamic faiths) decisions when it comes to daily matters. That means they reject their Gods guidance and reject his supposed teachings which he sent through messengers/Prophets. This is plain and simple means you reject God exisistence.
So your choice is to follow hypocrites of faiths who lie about being religious. Look what they do to the actual religious people like AQ/ISIS, they kill them whenver they get chance. This means Christians , Jews and Muslims are sick liars who despise the idea of religious society. Your other choice is to support AQ/ISIS. Your last choice is to not believe in religion. I no longer believe in religion since there is too many errors/mistakes/man made material in it. And because humans use it as a political tool/societal identity.
ISIS/AQ are just angry adherents of Abrahamic God who want to punish the hypocrites amongst their own abrahamic traditions. ISIS/AQ is like the little brother of Christianity/Judaism/Islam who recognize these capitlist liberal assholes who claim to believe in Moses, Jesus and Muhammad's ways of life are liars.
So the retards in these religions shouldn't pretend to be surprised with the trend genuinely religious groups who base all their worldly decisions of their faith.
I was religious back then. But even though I'm agnostic. I'd still prefer them over anything else. They're a lot more ethical than the capatilist cruel alternative we have in the world. Look at Iran , Saudi Arabia and Israel. Israel uses religion to fool American Christians into supporting their unjust colonial project. Saudi Arabia uses religion as tool to get Sunnis to fight in Syria and what not. Iran does same but with Shias. Meanwhile Israelis , Iranians and Saudis don't suffer any immediate consequences. Only the poor people who fight and die for their national interests do. Like the Americans, Arab shias, and other Arab sunnis.
These countries are wealthy and their people are mostly liberal/atheist but again pretend to be religious because its politically beneficial for them. In Islam that means you're a hypocrite damned to hell. It also means you're an infidel whos mocking God and using his teachings for personal benefit while you won't sacrifice anything for him since you reject him.
