I have observed, far too often in these forums, that there are people who are essentially intolerant of others who don't conform to one or another set of norms, views, beliefs, sexual expression, and so on. And I've also observed that there are many who are pretty accepting of all sorts of things, usually providing that they do no harm to others.
Now, I think (and this is based on no rigorous data) that the most intolerant people are very often those who are pursuaded by religious beliefs, often citing scripture to back up their intolerance. And I think that I've also observed (again with no rigorous data) that people who are more accustomed to free thought about everything (that is, not relying on scripture or dogma that is required to be believed) are much less likely to be intolerant of others -- often, in fact, being quite ready to accept and explore other viewpoints, cultures and so forth.
But many things impact our thinking, and religion (or irreligion), racism (or lack of it), politics, culture and so on inform how we relate with other people. But for my purpose here, I want to restrict the choice to just two: Are religious people more tolerant of human diversity, or are the non-religious more likely to be so?