I love the first 2/3 of the movie, but I think everything that involved the conflict with the soldiers was too facile. I prefer the original Night of the Living Dead and the Dawn of the Dead remake.
To Rid the Disease definitely did not remind me of any of those movies, however. I am confused by Akerfeldt's statement about the song being evil, and wonder if he was just trying to mess with people's heads. To me it's a fairly general song about loneliness and desolation, the tendency of painful experiences to result in great art ("This failure has made the creator"), and a reaching out to someone else who may have let the speaker down or is somehow responsible for his suffering. I wouldn't try to find a more definite storyline, because there simply isn't a concrete scenario in the lyrics.