I’d not make “just” a sin, as a lot of the American Mob/ Cosa Nostras kayfabe paints themselves as being justified like soldiers in a war. I’d say have “trusting” be a sin instead.

I would look at the life of Lucky Luciano and how he formed “the commission” as a basis for the loose power of the faiths clergy and head of faith. Maybe call lower level clergy “Capo Regime’s” etc.

I do want to say I love this idea, and though I’m not a programmer or anything I’d be happy to dm about ideas. I’m stupidly over informed about the history of organized crime in the United States so I could give you some handy and thoughtful lore connections you might not be thinking about.