Earlier quoted context omitted.
To the contrary, humans have never been nicer to each other or lived more pleasant lives at any point before the present.
And that's precisely because we stopped pulling this sort of crap in more and more places. 300 years ago, the number of religions and ethnicities currently existing in US or Western Europe would have meant a constant state of civil war.
300 years ago the Ottoman Empire was in full swing and quite religiously and ethnically diverse (probably more so than modern Europe or America). Not to say everyone had equal rights or was nice to each other, but historically a cornerstone for the success of many (not all) empires has been a significant degree of diversity and tolerance of both religions and ethnicity. It also wasn't new, Rome was also quite diverse and tolerant. (not always, not to everyone, but still quite so)