how many wars would there be if religion evaporated?

[BenNatuf]

Religion is a tool in war, not a cause for it. Wars are fought for power. So, there would be just as many without it as with it, they'd just find another tool.

 

[Quantum Windbag]

How many nations or peoples go to war claiming "God is not on our side"?

I don't know, but I do know some have. Communist China and the Soviet Union come to mind. Regardless, it is still the country going to war.

 

[American Horse]

I am thinking about 0

As an example, taking two centuries before and after the birth of Christianity: Rome, the most powerful republic/nation-state of the time spent 53-years in the first century BC at war. There were also the ongoing and chronic wars with Parthia (ancient state before becoming Persia proto "Iran") leading up to the first century AD, but in that coming first century AD (after the birth of Christ) there was only a single year of civil war, and eight years of external wars, again not counting the brushes with Parthia.
To recap; the score for Rome:
53 percent of the time at war 1st century BC
9 percent of the time at ware 1st century AD