From the second the story broke, I knew this was RaHoWa. Racial Holy War. This was a term coined by Ben Klassen who started the White Nationalist and antisemitic Church of the Creator. This was a thing endorsed by William Luther Pierce under the pen name Andrew MacDonald in his books The Turner Diaries and Hunter. This is a tactic endorsed by White Aryan Resistance founder Tom Metzger in his calls for The Lone Wolf strategy.
At this point, prior to the police interrogation, I am fairly confident that what Dylann Storm Roof carried out was not simply an arbitrary spree killing, but a calculated political assassination. There are a couple reasons I believe this. First, arbitrary spree shootings at black churches just aren't the White Nationalist M.O. If a White Nationalist carries out a spree killing, it's going to be in a place at a time where they can inflict the most casualties. A Wednesday night is not that time. Second, if your aim is to take out a Black church, you don't do it with a gun at 9pm on a Wednesday; you do it with fire and an accelerant on a Sunday. Third, White Nationalists, by and large, see Black folks as merely a pawn in an international Jewish conspiracy (often referred to as the Z.O.G. - Zionist Occupation Government).
The missing piece that folks appear to be missing in all this is that one of the nine dead was a Black state senator. This was a small gathering at which Roof knew the senator would be present, in close proximity, and would leave few if any witnesses. This was not a random shooting spree, this was a calculated assassination plot. I'm willing to bet anything.