Let's tackle the S&M business first. Reznor sets a sexual tone in the song's first verse, singing "God Money, I'll do anything for you," which becomes sexually charged with the subsequent line "nail me up against the wall." As the speaker begins to resist the demands of God Money, the song deviates from this sexual focus to become more vaguely focused on all forms of control. Given the first verse, however, the second chorus' lines, "Bow down before the one you serve / You're going to get what you deserve"—which seem to be spoken by a different character (or characters)—definitely imply some sort of sexual mayhem.
Since "God Money" has already established a pseudo-religious frame for the song, the lines between sex, the soul, and religion become blurred in a very provocative, if not inflammatory, way. Religion is a much more obvious theme here than S&M is. The submissiveness of the first verse—"I'll do anything for you," "just tell me what you want me to," "nail me up against the wall"—evoke religion perhaps just as much as sex; the fact that Reznor doesn't draw any sharp line between where one ends and the other begins is the origin of much of NIN's controversial presence in American pop culture. It could, in controversial terms, be argued that Reznor is implying that the worship of a God (especially a pleasurable, hedonistic one like Money) is slavery equivalent to the slavery of sexual role-playing. That is, your religious master is not too different from your sexual master. Needless to say, lots of folks find that kind of thinking deeply offensive to their spiritual worldview.
In "Head Like a Hole," God Money is much more than the mere suggestion of the false god Mammon that appears in Matthew 6; here the worship of God Money hedges into outright Satanism. Reznor expresses this in the chorus with the obvious connection between darkness and evil in "Head like a hole / Black as your soul." The verses tell a more interesting story, with God Money's actions seemingly directly opposed to the actions of the more familiar religious figure of Jesus. You might even call God Money the Antichrist. Where Jesus was the victim of crucifixion, God Money becomes the crucifier in "God Money, nail me up against the wall." Where Jesus was universally referred to as a healer (in all the religious texts in which he appears), God Money is simply "not concerned about the sick among the pure." And where the meek would have inherited the earth, God Money "dancing on the backs of the bruised" presents an opposite image: the meek becoming the earth, trampled on by the evil.
Of course, the name of God Money links this imaginary false idol to our own mass-consumer, capitalist tendencies. As the song closes, with Reznor screaming, "You know who you are," it becomes clear that Reznor might just be aiming his bile at… us. "Head Like A Hole" attempts to shame our greed by tying it to sexual humiliation and spiritual damnation. Those metaphors are nothing new; when you feel you've been ripped off you might say you "got screwed"… although you're not likely to spend too much time thinking about the ramifications of that metaphor. What makes "Head Like a Hole" so uncomfortable is the stark way that Reznor demands that we really think about exactly what that means.