When the attorney is discovered with his stomach cut open and the word "greed" written in blood on the carpet, the detectives know something is up. Even though the gluttony murder is discovered first, the name of the sin is hidden behind the fridge. Here, it's out in the open. The lawyer's sin is public. The fat man's sin is private.
"Long is the way, and hard, that out of Hell leads up to Light." (Paradise Lost)
This quote is on a note left for the detectives by the killer. Paradise Lost is about original sin, so it's appropriate that the killer leaves his note at the site of his first murder.
SOMERSET: There are seven deadly sins, captain. Gluttony, greed, sloth, wrath, pride, lust, and envy. Seven.
Everything so far has been a setup for this. This serves the purpose of letting us know the killer's religiously influenced motivation and adds suspense. Seven sins means seven murders, and knowing what to anticipate makes the movie more suspenseful, not less.
We've got the lowdown on these sinful texts, too. Somerset plays closest attention to "The Parson's Tale," about the parson who needs to lead by example. If that's true, what example is Doe setting?
SOMERSET: The sins were used in medieval sermons. There were seven cardinal virtues and seven deadly sins used as teaching tools.
If the murders in Seven were real, what, if anything, would they teach you? Would you be careful not to sin, afraid that Doe would get you?
SOMERSET: The sermons were about atonement for sin. These murders are like forced attrition. [...] It's when you regret your sins but not because you love God.
John Doe is a religious zealot. He's not doing God's work. He's enjoying being a serial killer with a so-called purpose.
JOHN DOE: Only in a world this s***ty could you even try to say there were innocent people and keep a straight face. But, that's the point. We see a deadly sin on every street corner, in every home, and we tolerate it, we tolerate it because it's commonplace, because it's trivial, we tolerate it morning, noon, and night. But, not anymore. I'm setting the example. And what I've done is going to be puzzled over and studied and followed forever.
Even though this is fictional, it's true—we're still puzzling over, studying, and following John Doe's motivations more than 20 years after the movie came out. What makes this film so compelling? And, do people sin more now, or less?