The attached link explains that wars can explain a lot about which countries today follow which of the world’s great religions. Wars determined much of the distributions of religions around the world, but it’s even more striking to recall how some wars turned on one of two individual battles which could have gone either way.
What appears to have eventually effected the U. S. was the Thirty Years War in Europe (1618-1648). This was a war the started between Protestant and Catholic countries in Central Europe who were part of the Holy Roman Empire. Catholic domination was weakened by the war and Northern European Protestantism were strengthened.
Thus, Protestantism was the religion of choice of those who came to the U. S. There were virtually no Catholics among the Founding Fathers.
It is sometimes argued that the Crusades weakened the aggressive Islamic countries of the Middle East so much it prevented Islam from being imposed on Europe and later the U.S.
The author correctly points out relatively few resources have be invested in studying the impact of wars on the religious landscape. When I see the huge volume of published material devoted to arguing about what a religious book like the Bible means, it’s obvious there is comparatively little material about where and how various religions came to dominate.
It is encouraging to see at least a little interest in studying where various religious ideas originated and the roles of wars and governments in their distribution.