Ugh... I would rather not think about WW3. There would be lots of nukes. Russia, China, USA and the Middle East would be big players. and there would be lots of nukes. No one would win. Did I mention there would be lots of nukes? this video pretty much sums it up
I'm gonna leave that to God. It's good to prepare for another world war, though.
Your right. Religion will probably start it. Since there is no god and everything is random chance, and if the war has nukes, I would have to give the victory to the atheist in foxholes.
By the time of WW3 there will be three distinct factions: Totalitarianism (One man owns all), Islam (God owns all), and Christianity. I think, by the end of WW3, Christianity will be eradicated and the whole world will go for a totalitarianism rule.