The subject of this song is simply conformity, but Radiohead takes a closer look at it, and discovers the difficulty in resisting conformity, especially in a confusing world so confusing that "2+2 equals 5" and "January has april showers".
The songwriters' tone is resistant but indecisive. He first claims to feel incredibly passionate about resisting conformity. "It's the devils way now." but then at the very end of the song all of the built up passion of this resistance falls to the questioning lyrics, "maybe not, maybe not".
The the theme is, the appeal of conformity is often hard to resist. This can be seen in the song lyrics, "No way out", meaning there's no way out of conformity.
