European Islamic State in Iraq and Syria. lol. How would that work?

islamic state in italy and spain or ireland and slovenia

ireland and scotland would be funny. i dont think islam can win vs guisnness and drinking because you have nothing to do...

Well that wasn't the initial cause of the Viking age though it was a later motive. Initially they simply extended their traditional raiding to the British Isles where they found an absurd amount of undefended wealth in monasteries, and this kicked off something of a gold rush. I suppose it depends on how you look at the character of their expansion, as it was indeed motivated by excess sons in a gavelkind system of succession where all were expected to receive land and fathers wanted to acquire enough for them all. Simultaneously, though, there was a cultural/religious motive that really mirrors that which you find in the Iliad or Beowulf, where a truly great man could only be so through renown from exploits martial or exploratory. The shortage of arable land further contributed to this... As you said earlier, there were a great many factors involved here.

The crusades are rather different though, insofar as land was not as scarce and there actually was a great deal of infighting despite the Papacy's attempts to stop Christian on Christian warfare. When it became clear they couldn't stop it they began establishing guidelines which, more often than not, were followed. I have no doubt this was one consideration in launching the crusades, but it certainly wasn't the biggest one.

Each crusade was different in nature so it's irresponsible to generalize, but what you find is that most participants from top to bottom of the social hierarchy were primarily motivated by faith, especially in the early crusades. What you find when looking at the first couple crusades is that the vast, vast majority of participants were the lowest rung of the social ladder, fighting on behalf of Christendom with no hope of temporal restitution for their efforts. The gentry and many nobles, meanwhile, were conscious of all their sins and leapt at the opportunity the crusades presented, as to die on crusade was to gain immediate admittance to heaven without any waiting in purgatory. Indeed, most had to sell much or all of whatever possessions or holdings they had just to finance the venture.

That's really the key evidence for these first couple crusades; nearly all participants went all-in, selling their worldly goods or, in the case of many wealthy noblemen, spending vast sums of money and risking their holdings back home just to make the journey possible. Contrary to what people like to say lately, there was virtually no chance of actually gaining wealth from this endeavor except for a few noblemen, and even then the costs and risks far outweighed any possible gains if one was going solely for temporal (not spiritual) reasons. It took a few minor miracles and good timing for them to succeed at all and, once they'd gained the holy land, the VAST majority returned home, largely dispelling the "we need more land" theory. It benefited those nobles who held the newly formed territories as they could give these titles to potentially troublesome sons who were not otherwise in line to inherit, but there were not otherwise many tangible benefits.

As time went on the crusades certainly became more akin to the tool you describe and increasingly less people would participate while the ventures would grow more organized and professional, but there is little getting around the idea that the first few crusades were propelled more by faith than any other factor. It's difficult for us to see it that way, but that's because we must adopt the mindset of a medieval European to understand their motives and priorities. Faith, even among most of the gentry and nobility, was taken enormously seriously.

That's what the anti-religeous types never seem to understand - at most religion is an excuse for things people do.  There is always a socio-economic reason for everything, including the crusades.  

Take some college courses people, people do things because they need or want to, and then they use religion as an excuse for themselves and others.  They aren't some army of God, they are angry sociopaths.

Completely agree about religion as an excuse to wage acts of violence.

But IS seem so convincing that they have an actual agenda. They have plans, ideology, other literature. Even if most of the footsoldiers are just brainwashed, I think some genuinely believe they're doing, in this case, Allah's wishes.