Okay, this is already "religious". Just because TMP's Editor has dictated "no politics, no religion" on the "real" boards, doesn't eviscerate the religious aspects of our current "world war". It is a relatively small world war, so far, compared to the full-sized mobilization, battles and "total war" of the two previous world wars. And this one has zero connections to that "thirty years war of the twentieth century". This world war is a thing apart. Yet many players in those two world wars are involved in this world war, and are even ingredients in the causes of it.
There is a "rhyme and reason to this". Things that people do are never without "rhyme and reason". You just have to find out why "those people" exist in the first place, and why they are doing this. That is where "history" comes in. Without "histories" (theirs and ours) inculcated by societies, there is no casus belli for demagogues to preach; no justification for their acts of aggression and violence; no reasons why anyone should be upset by, or support, the war that the terrorists launch.
History, or rather, "histories", are the first line, the core attack and defense.
Theirs is all about Europe and the "West", the "great Satan". It has been for generations. This is nothing new. It is getting to be very, very, very old. And the same religion is used each time.
I agree, it isn't "about religion". It is about manipulation. Societies and cultures manipulate themselves, their rising generations, to believe in a version of history. Their version. And of course, it does not dovetail with the history understood by the other side; our side. We share more in common than we disagree on. That is because our universities and lower education institutions have been listening to each other and preaching the same version of "history" for as long as the traditional enemy as been preaching an alternate, "other" version. Religion has played a central role in all of the earlier wars: both to launch the "holy war" and to respond to it.
The origins of either religion are similar, though separated by centuries: they arise out of what we conveniently call today "Judeo-Christianity". And Judaism is very, very, very, very old. It grew out of paganism, which is older still, going back to prehistory (before anyone was writing/recording anything).
What we are dealing with here is the same old same old human darkness. Let's do try and not get over ourselves. This really is all about us as a species. We've come a long way over the millennia that we have kept track of ourselves, that we have kept any kind of "history" about ourselves. And, universally the sin of "history" is manipulation of it. Truth is the first casualty when self-interest rises up to dominate all other considerations or factors that go into the mix of "history".
History doesn't just become slanted toward self-interest, it serves self-interest above all else.
Right now, the world war is all about overthrowing the existing old order of the imperial colonialists. The benighted insurgents and terrorists appeal to any and all elements within the "imperialist" regimes to join them. First and foremost are the asserted "coreligionists". But any who are adrift enough to "convert" to the terrorists' brands of "Islam" are welcomed with open arms.
So we've seen thousands (from billions) flow unto it. ISIS is not the only player seeking to dominate and bring down the imperialist order. 
This will not stop. But it must be understood. And understanding is the first essential to combating any danger. Without understanding there can be no focus on victory.
If we do not obtain victory very soon over this plethora of terrorist groups, they will continue to portray themselves as a "bloc" of belief and motivation. They really only have one thing in common: mutual hatred for being marginalized by a complex of politico-economic factors, put in place by "the West". The countries where these people originate are benighted economically, marginalized by the soullessness of capitalism and imperialism that thrusts itself into those countries to exploit their resources for gain.
The danger isn't specifically any one group. So yes, this isn't "about religion" at all. But don't lose perspective here. If we, their targeted enemies, do not recognize their casus belli as an asserted one that is religious, we will not appreciate the intended target of their preaching: Muslims everywhere. That religion is their most natural recruitment pool.
And because there are very large Muslim enclaves in many European cities already, some of them well in excess of ten percent of the population, and because they have largely not integrated, but rather form entire communities (enclaves) where their religious ideas control their daily lives, and most importantly, because they are economically marginalized (moving to live in relatively prosperous Europe and the Americas has not substantially given them more quality of life), their education opportunities have not been realized, they do not rise in the world, they must serve masters of the "old imperialist order" still. And because they feel this way in their millions, they pose the very danger to the "West" that the terrorists want.
The only way to eradicate these attackers is to put down the terrorists as an overt danger. While terrorists can wage open war, they pose a recruiting force. Their very asserted casus belli is religious: and radical Islam depends on open warfare. It must exist politically. ISIS, Bokoharam, Mujahidin, "Muslim Brotherhood", et al. any of them must obtain and grow political power. The "caliphate" must be established and it must grow. Without that essential existence, radical, jihadist Islam cannot be appealed to as the reason for the war.
Much more insidious than religion is an ideology that can be formed out of whole cloth, something secular and "new". So we should be feeling fortunate that this danger possesses such a weak spot. It cannot justify itself by appealing to a religious mandate that does not exist.
So "the West" has a number of clear targets. We can band together, unite with the Muslim majorities in those countries where overt jihad is trying to mutate the Muslim populations into "holy warriors" through terrorizing their own into submission. But if there is no organization portraying itself as the "caliphate", and incapable of operating as openly "holy warriors", then there will be no inducement in Europe for Muslims to "unite" to such a movement.
That is why ISIS must die. All openly organized Islamists must die off. Forcing that extinction is the tricky part. Because "the West" has its own ingrained memes that play to the "history", that forms the "players" that the terrorists and their sympathizers rightly castigate for their "imperialism". We do not have "right" on our side. We have justification and outrage. But so do they, and it all goes back a very long ways into their "history", which overlaps with our "history". But those competing histories are at war with each other. The details are the devil. And all that the devil wants is mutual destruction…………………
out of me.