The Crusades and Jihads, like every other war/conflict was never really about religion, but struggles for power and resources. Religion and political ideologies are only convenient pretexts to war.
If we somehow manage to solve the problem of limited resources, big scale conflicts will greatly diminish. And, the good thing is that we are slowly getting there. Fusion technology is getting closer to be realised, bioengineering (our search for cures for diseases and ageing) is constantly developing. Then we have the not so unrealistic concepts of nanotechnology and quantum computers that, in theory could solve many of our problems.
The reality is almost no wars are fought for want of resources. The underlying argument implies that only resource starved nations or states (or planets) would or should be belligerents. While obviously, resource rich nations would have no need for war. Obviously, historically, that is not the case...exactly the opposite.
Take for example this: In 1991 Iraq (one of the worlds top oil producing nations with one of the highest standards of living in the ME) invaded Kuwait to among other things control it's oil fields as well. Clearly this was not a case of war caused by a "pressure for resources" since Iraq controlled many times the amount of oil as Kuwait did, and was nowhere near exhausting it's own supply.
By comparison modern Turkey has no oil fields and precious few other natural resources and hasn't been involved in a conflict since 1918.
If wars were truly fought over the "pressure for resources" or some other such dispute we would expect nations like Turkey to be aggressors not those like Iraq.
The only way resources become involved in the equation, is because the rich power elites of a particular nation have a desire to control and hence profit from the control & distribution of other resources beyond those they already control (usually in some other nation, often controlled by some other group of power elites).
When it comes to "fighting wars over 'strategic' resources" the operative term is "greed" not "need."