Dr.Sid
Philosopher
There are millions of white Baptists in the USA, especially in the South.
ETA: And here is their Facebook page.
My bet would be on a member (or former member) with a grudge.
My bet would be another bored want to be famous idiot. Based on statistics. But srsly, people like that would kill even without guns. I wouldn't invest much hope into gun control in this regard.