Look, I get that for a lot of southerners today the confederate flag is about independence, rebellion and regional pride. So I don't get pissed off at people that display it.
That being said, the civil war was absolutely about slavery. All that garbage about states rights and crap was the lies the rich and powerful southerners told the poor ones that would be doing the actual dying on the front. See, they might not have had a big problem with slavery, but most of them would have been willing to die for it.
Anyway, if you actually look at the history from the time period leading up the the civil war, you would notice that southern democrats had almost all of the power. One of the reasons the north was willing to fight the war at all was because the south had been making serious, largely successful, efforts to functionally force slavery onto states that had outlawed it, and the north was afraid that if the south became independent they might become even more powerful, and thus even more successful in those efforts. Slavery might not have been the only issue on which the north and south disagreed, but it was the only one they were willing to kill each other over, and thus it is the only one responsible for the civil war.
I have nothing against the south of today. My family was all too far out west already by that point to really identify with either side in that particular conflict, but the south of the civil war was the last bastion of legal slavery in the western world, and they absolutely deserved to get their asses handed to them. The north wasn't particularly good, in fact they were frequently downright horrible, but the south was absolutely and totally unequivocally wrong. That's okay though. Hitler was wrong too, that doesn't mean there's anything wrong with modern Germany. As a matter of fact, it's a pretty cool place. But the south of today needs to come to terms with what they really were before I can respect their desire to wave that flag around. I don't blame individuals that don't understand or believe what it really means, but as long as they don't this discussion needs to continue, because the people pointing out how horrible it is are right until someone really changes what it means, which I don't think can be done until the people who use it admit it needs changing.