I've no idea how one would untangle the web of religion and secular purposes and I really don't care.
I suspect that few could as rather than the three threads that we have in the west, Islam is all three in one thread. The Fundamentalist sees the world as containing three main Imperial Ideologies, Communism, Capitalism, and Islam. While we recognise that Eastern Communism was separate Extreme Socialist economic policies, State atheism, and single party totalitarist politics, while Western Capitalism is separate free market economy, Christianity, and democracy, Islamists see those three things mixed together as one just as their own understanding of the Islamic Ideology. To try and separate them as we have in the western and eastern counties would not make any sense to an Islamist.
All I care about is A.) religion provided for the moral authority for the attacks.
To a point. Attacking back at the invaders/crusaders, attacking those forcing western culture on the world, bringing the remaining opposing ideology to its knees, getting the US to leave the Middle East and cease its support for governments there, these are all just as valid reasons to give moral authority for the attacks as well.
You keep conflicting "moral authority" and "divine moral authority". If I believe that you are immoral because of what I see of your actions I don't have to believe in a supreme being to claim moral authority, I just have to claim my morals are greater than yours, and if you start trying to push your lesser morals on to those around me and kill them with your flawed ideals in what I see as an effort to destroy my society, that can still give me moral authority to attack you for it, all without a supreme being.
The issue in RL is that most people's morals have been guided by religion of some sort for thousands of years, so it is hard to unbind morals from religion.
B.) By your logic there is no such thing as a religious war.
I'd say welcome to reality, but I get the feeling you still won't agree with this. I'm not discounting that there have been wars fought purely because of religion, I just have yet to find one.
Conflicts are always complex and dynamic. I only care if religion is used to manipulate and exploit.
I agree that conflicts are always complex and dynamic and it's often hard to pin down the exact causes of most of them, for instance while the initiating event of WWI was the Assassination of the Archduke, the reality is that the war was inevitable as the political tensions had grown to a point where a single spark was going to explode the powder keg. The assassination provided that spark, but if it had not happened, something else would have soon enough.
The thing is that politicians will always use whatever they can to manipulate and exploit their populations when they want to go to war. Religion is just one arrow in the quiver, they are just as willing to manipulate patriotism or something else. That it can be used to manipulate people does not make religion a bad thing, any more than anything else that politicians twist and use. The one consistent factor in all wars are the politicians.
For the record, I believe that Bin Laden was sincere in his religious beliefs and his anger with American incursion into holy lands. And, BTW, I'm not judging them by any standard. You don't even know my position on 9/11.
I agree that OBL was very sincere in his religion, I also know from reading a huge amount of material about him and AQ and their actions previous to and leading up to 9/11, that he was just as passionate about the politics of it all. This becomes very obvious in the selections of targets. Embassies, Ships, The WTC, The Pentagon, the Capital. These are symbols of the US's political and military power, not its religious power. The attacks were against symbols of the US political power because they were from a political motive, even though that motive was enmeshed with religious belief.