Life isn't random. It exists because it can exist and the successful variants of life flourish and grow. Humanity is just an advanced form of mould on bread. It's pretty much all based on chemicals and environments. If you are interested in it, you should read into it, it's much more amazing and interesting than any religion despite being more convincing.
For instance, "Religion is notorious for not letting others 'live and let be'".
This is the elementary school version. The convenient fiction told in between the messages on civic virtue and the joys of socialism.
In the context of your meaning, religion is a inanimate tool. No one has ever died for religion or killed for religion. Religion is the excuse for their actions, what they used to attempt to justify their actions. They died for their own purposes or killed for their own purposes.
It is ridiculously naive to point to the convenient excuse used by the perpetrators of violence as the cause of their violence.
Like the amazing churls who seem to think the Crusades were about religion. Really? Where is your evidence? Because people on both sides prayed a lot?
Or people who think the Reconquista was anything about religion. Really? Is that why more Catholics were arrested, tortured, murdered and forced from Spain than any other religious group?
If people think that their religion rewards them for an act of violence then you could argue that it is one of the most strong incentives a person can have.
Yes. You are correct in stating that people can, and sometimes will use religion to justify their actions. But when was the last time that was actually used? As far as I'm concerned, it was with the Reconquista days like you said. And they were only fighting in their religion's name because they thought it was the only way their way of life would survive. Obviously they were wrong in everything they did, but they were young and stupid. Not much we can do for them now.
Contrary to what the state-controlled media would have you believe, al-Qaida is a political organization.
So-called "Islamism" is a political movement.
They use religion as a recruitment tool, as a morale booster and as an excuse.
Certainly their political goals are based in a philosophy built from a religion; however this does not make them a religious organization.
Secular humanism is based in a philosophy built from a religion, but you wouldn't go out and call Albert Camus, Einstein and John Lennon religious extremists and you wouldn't call the Skeptics Society a religious organization.