Ideological differences are a major source of arguments turning ugly and lots of downvotes, if you disagree with whatever majority in that particular forum.
Hmm. That sounds like it can be frustrating, but I can see how it can happen. For example - what's the point of claiming "white people didn't invent slavery?" I can't think of any reason that doesn't involve a blanket statement about either white people or some other race, which would be prejudgement/prejudice by definition. Hence, smacks of racism. Similar for statistical differences in social groups - dangerous territory as it is what "rational racists" try to do all the time. I use those statistics all the time though to demonstrate that it's impossible to prove that a group of people have a certain average IQ or some other grab bag trait because of race, due to noise from other variables like socioeconomic status, local culture, local healthcare availability, local government policy, etc.
I could easily say that in response to a claim that white people invented slavery, in total innocence that somebody would read me as racist. I am somewhat naive, in my defense.
Conversely I've also been called a racist/bigot for claiming white people didn't invent racism/slavery, or that statistical differences in social groups shouldn't automatically be attributed to oppression, or that Frederick Douglass is evidence of how someone can free themselves from oppression.
They obviously had never studied MLK, Frederick Douglass, or world history, though I'd bet they had spent plenty of time watching cable news and shallow mass media.
The reason they called me those things was not because I was actually espousing hatred, but rather because I was suggesting something antithetical to their ideology.