Here's where I'd forgive displaying a Confederate flag in some way, shape, or form: IF you had an ancestor who fought in the Civil War for the South, and who wasn't overtly racist (I.E one of the folks who joined up to fight for their state, and not necessarily slavery [I know the war was fought over slavery, but there were individual exceptions inasmuch as individual motivations for Southerners joining up is concerned.]) then I am 100% fine with you having one in your home or something. That's part of your history and I don't think it's fair for anyone to tell you to suppress.
I do have a problem with the people who use them as some sort of rallying symbol, especially as a Republican symbol. The Republican party was in fact created to end slavery and other racism in the U.S, so anyone who says they're a Republican but carries one of those flags to support 'muh freedom' is an idiot.