Hate the Sin, Kill the Sinner
John Doe leaves quite the bloody trail of victims over the course of a week, each one targeted for personifying one of the seven deadly sins.
The first victim discovered is gluttony, a gigantic man found dead, face-first in a pile of spaghetti. It takes four orderlies to get him on the table at the morgue.
The second victim is Eli Gould, a sketchy attorney who defends pedophiles. He is forced to cut off a pound of his own flesh. The word "greed" is written in blood on the carpet.
One of the pedophiles is Victor Allen, and he is the third victim, the sloth (making him a lazy pedophile, we guess). Doe keeps him chained to his bed and starves him for a year. He's practically a skeleton when they find him, and one of the cops remarks, "You got what you deserved." Even the doctor is unsympathetic: "He still has Hell to look forward to."
Next is lust, probably the most gruesome murder in the film. A man is fitted with a codpiece that holds a Bowie knife and forced to have sex with a prostitute, killing her.
Then there's pride. Doe cuts a woman's face and gives her two choices: "Call for help, and you'll live, but you'll be disfigured. Or you can put yourself out of your own misery." She has chosen door number two, taking the sleeping pills he provided her with.
None of these people seem to be missed at all, which kind of proves Doe's point—maybe people will see these victims and try to be better people so they don't end up meeting the same fate.
Now, if you can count, you'll see we've only listed five sins. The last two, wrath and envy, are the final two. Doe himself is envy, jealous of Mills' happy home life and pretty wife. So, he kills her. This prompts Mills to become wrath and kill Doe, completing Doe's mission.
Is his mission a success? Doe falls into the same category as most of the victims, someone whose presence in the world won't be missed. Doe's death might even be celebrated. But Mills is a sympathetic character, so making him into a victim seems to negate the whole plan.