Hmm. Is the intent to have the costume represent the sin itself, or someone who is guilty of the sin?
By your wording, I’m guessing that you wish to represent the actual sins themselves, which is inherently more difficult.
Here are the 7 as represented by some Australians in '02. Might be good for a few ideas.
To represent the sins themselves, I think color is definitely a major consideration. Red with anger (as you’ve deduced), green with envy, etc. Harder for the rest. Maybe black for Greed?
Some random thoughts:
-Pride should carry a mirror. Or a bullhorn. Depends on the party I guess. Something that demonstrates their self-importance.
-Gluttony should have a food item (plastic turkey leg? ham hock? half a banana stuck to their shirt?)
-Perhaps Greed could be bedecked with jewelry and fine linen, and Envy be a crude mock-up.
-Sloth always makes me think of the animal.
An amusing option: The cast of Gilligan’s Island
I recall a while back a humorous article making the rounds of everyone’s inboxes detailing how the residents of GI were physical manifestations of the seven deadly sins.
Paraphrasing from memory:
Pride = The Professor. You’d be overly proud too if you could make a radio out of coconuts.
Lust = Ginger. She oozed sex appeal, and always dressed the part… even while stranded on a desert island for years.
Envy = Maryanne. She was envious of Ginger’s beauty, and ability to look beautiful all the time.
Greed = Mr. Howell. He took a suitcase full of money with him on a 3 hour cruise. 'Nuff said.
Sloth = Mrs. Howell. No explanation required.
Anger & Gluttony = The Skipper. Even after years on a desert island with no meat, he manages to remain overweight. And he was always very quick to strike at Gilligan with his hat.
Which leaves Gilligan, who was, of course, the Devil. It was always his fault that the rest of the “sins” were forced to remain on the island.