Bigotry is an unfair prejudice against some group of people.
This prejudice has many important negative effects on a person. It causes people to exaggerate stories in certain negative ways, focus on some actions and ignore others of the disfavored group, be more likely to accept negative stories about the disfavored group, etc. This can often lead to hatred and hatred can lead to violence or social exclusion.
Obviously, bigotry is bad. But there has been a tendency recently to label all bigotry as equally bad. Instead of being against a certain kind of bigotry (racism, sexism, etc.), we are supposed to be against bigotry in general. Now, I am against bigotry in general. Sure. But I do think that there is an important sense in which not all bigotry is equal. Some bigotry is morally worse than others.
It seems intuitive to me that a prejudice against blacks in a society that has a long and nasty history of racism is a greater wrong than an equally strong prejudice against people whose names begins with the letter M. Imagine that both of these people are severely prejudiced and often act on their prejudice. Why believe that one is worse than the other? Because of the effect that it has. Given the history and cultural context one prejudice is far more significant than the other. It is likely to be shared by other people in the society (either explicitly or implicitly.) Many small acts on the basis of this prejudice will create social structures and habits that disfavor certain groups, etc. It seems to me, therefore, as though the racist in this case is far more culpable than the letter-M hater. Even though both are equally prejudiced.
And this is the key point: history matters. Prejudice does not exist in isolation as some irrational tendency that is more or less randomly distributed throughout society. Rather all prejudice is socially conditioned and has an integrated context. That context matters. When one shares a dominate prejudice within one’s society, then one participates in a harmful institution. When one has an idiosyncratic prejudice, however, one does not likely participate in any pre existing harmful social institution. The effect is really small. Thus, we can conclude that some bigotry is in fact more harmful and more wrong than other bigotry.