The scariest thing in Sinners is not the vampire. It's the invitation.
Most horror films make the monster the problem. This one makes the door the problem. Who opens it, and why they were desperate enough to.
Ryan Coogler set a vampire siege inside 1932 Mississippi and fused it to Hoodoo protection work, Delta blues mythos, and the real arithmetic of company scrip. The folklore isn't decoration. It's load-bearing.
I wrote about how the film uses threshold law, music as ritual, and a "freedom" offer that always charges interest later.