" Only after 1700 did things gradually change. The widespread and terrible suffering that Europeans endured during the wretched wars of religion had made some people wonder if it was really right to judge someone by his or her religious belief. Was it not more important to be a good and honest human being? Would it not be better if people got on
with one another regardless of any differences of opinion or belief that they might have? Better if they respected one another and tolerated each other’s convictions? This was the first and most important idea that the people who thought about such things now voiced: the principle of tolerance. Only in matters of religion could
there be differences of opinion. No rational person disputes the fact that two plus two makes four. Therefore reason – or sound common sense, as they also termed it – is what can and should unite all men.
In the realm of reason you can use arguments to convince others of the rightness of your opinions, whereas another’s religious beliefs,
being beyond rational argument, should be respected and tolerated. "

― E.H. Gombrich , A Little History of the World