I would argue that GrumpyFlumps is actually right, it makes no difference whether religion was the pretext or the reason.
It makes a very big difference whether religion was the pretext or the reason in the context of my arguing against the statement another poster made that 'most of the wars of history were caused by religion'; if you want to put it into some other context and then say the argument is 'meaningless' is another matter, you could put my argument in a context that has nothing to do with my argument, such as the context of 'what's better, oranges or banana pie' and then really zing it home to me that my argument is 'meaningless'; it doesn't change anything in respect to my argument being very valid taken in the proper context for which it was intended.
A leader can want something for non-religious reasons that requires war to get. But if religion causes them to believe they are entitled to take it, motivates their followers to fight for them and justifies savagery in the execution of that war then religion takes the large part of the blame for that situation. For its only role to be as a justification for war all/most of the people supporting the war would have to be in on the real reason, with the justification being just an excuse for the other side and third parties. I don't think that's the case in history.
This argument shows a misunderstanding of what is commonly understood by the term 'cause'. None of your explanations satisfy the criteria for being a 'cause', not in a broad, worldwide, all-history viewpoint way.
Is religion the material cause? [The material cause of an object is equivalent to the nature of the raw material out of which the object is composed.]
No.
Is religion the formal cause? [Formal cause is a term describing the pattern or form which when present makes matter into a particular type of thing, which we recognize as being of that particular type.]
Again, no.
Is religion the final cause? [or telos, is defined as the purpose, end, aim, or goal of something]
There are some historical precedents for this, specifically I think the Mohammedan conflicts in the early days of Islam would possibly be described in this way, in so far as the wars had a religious goal in mind. On a worldwide and entire history view however, there aren't a great many examples of this sort of thing taking place. Amongst polytheistic religions of which the world in a majority way previously consisted for the majority of civilization, religion rarely was cause for strife between peoples.
Is religion the efficient cause? [The "efficient cause" of an object is equivalent to that which causes change and motion to start or stop (such as a painter painting a house)]
Religion does not 'cause' this motion, it might help to facilitate, but if you use this as your argument you can argue virtually anything as being the 'cause' of wars, including but not limited to: life, food, oxygen, water, writing, reading, intelligence, hair, toes, fingers, wheat, etc, in so far as all of these help facilitate the conduct of war, but no one would think to describe them as being the 'cause' of war. Admittedly ultimate causes for wars are very difficult to pin down, I don't claim to say why this and that war was waged, but with this nor am I simple-minded enough to simply ascribe them to 'religion' as the 'cause', tho it often may be the casus belli for wars. There's the famous historical example on which the Iliad is based, the common idea is that the war was waged over one woman Helen, many historians however contest this idea and say the ultimate cause for the war was to control a vital geopolitical location. Nobody knows for certain, possibly not even those who initiated the war originally. Why does any of this matter? Well, if you are going to paint black the entire domain of what is encapsulated by the term 'religion' by saying that 'religion is the cause of most of historys wars' then I take issue with this and think this very wrong idea should be challenged and shown for the fluff it really is.
I wouldn't downplay the significance of europe and the middle east as a part of the world, particularly in this context. For western culture, it was effectively the entire world up until a few hundred years ago. And certainly when westerners talk about religion in history, they are mostly referring to its place in the history of the western world.
Eurocentric.
I'd have to see some evidence that the crusades would have happened without the influence of religion before I would call a religious motivation for them questionable.
Go to the library and read a book. Or, do what most people do, read the wikipedia article.