Off the top of your head, which atrocity was worse:
Spanish Inquisition - perpetrated by a mainly Catholic country
Rape of Nanking - perpetrated by a mainly Taoist country
I suspect that you've heard much more about the Spanish Inquisition in school, but the "Rape" makes you think that maybe it was pretty bad too.
The Spanish Inquisition lasted from 1478 to 1834. Total Deaths: 3000-5000. Maximum average per year = 14.
Rape of Nanking lasted 2 months from late 1937 to early 1938. Total Deaths: 200,000 to 300,000. Other atrocities include the fact that "80,000 women were raped, including infants and the elderly". The savagery surpasses the worst torture in modern horror films where "The women were often then killed immediately after the rape, often through mutilation, including breasts being cut off; or stabbing by bamboo (usually very long sticks), bayonet, butcher's knife and other objects into the vagina."
Glad to see that our history education in America prioritizes atrocities by scale, and not by vendetta against a particular religion.