Sin was a term used to describe certain acts considered to be bad. A person who committed sins was called a sinner.
In 2266, discipline broke down aboard the USS Enterprise as a result of polywater intoxication. Among the resulting incidents were the painting of graffiti, admonishing "sinner repent". (TOS: "The Naked Time")
In 2366, Tam Elbrun told Data that being different was not a sin, though he thought the android may have heard otherwise. (TNG: "Tin Man")
When The Doctor role-played as Father Mulligan in the holoprogram Paris 042 in 2376, he often labeled people sinners. (VOY: "Fair Haven", "Spirit Folk")