I think the point was that secular wars are generally for resources. Nuclear war practically eliminates the possibility of gaining resources, because you're likely to lose more than you gain as your cities get vaporized. So the drive to start one is significantly lessened. Religious wars on the other hand, all bets are off. You're doing it for salvation, so even if the victor ends up poorer for it materially, it's still worthwhile to start.

What do you think "Jihad" means in the context of the September 11 attacks?

Sorry if you are effected by it, but on the grand scale of conflicts the attack on the trade towers was pretty small.

Also if you want to get really nit picky one could argue 9/11 was more motivated by geopolitics.