Very good question copperbod for which as far as I am aware from 'recorded' history there has always been some form of religions - which were not always the cause of wars as there have been nationalistic & ethnic wars which if they did nothing else momentarily kept the population down
Perhaps that is natures way of having a say in 'things'.
So in conclusion I have no evidence that the world would be a far better place without religion.
However as humans are the cause & religion Is the effect (or is it God's fault) then the problem is solved by ridding the world of humans - one day it will happen !!