Pointing to an existing injustice and saying “that is wrong and must not stand” may create discord, but not division. The inequality is the division. Pointing it out no more “creates” it than turning on a light in a dark room “creates” the room.
While “White Power” and “Black Power” may be superficially similar, both the historical context of the United States and the way each of the phrases are/have been used make them different in extremely meaningful ways.
The Confederate flag is indeed a symbol for everything for which the Confederacy stood, and the Confederacy stood for the maintenance of the institution of slavery, first and foremost.