I'm not a fan of rude people.And I'm not a masochist,either, so I don't like being mistreated by them.And nowadays, as 2 Timothy points out, people are getting worse.That being said,is rudeness a sin? Some sins are specified in the Bible, others we have to "look deeper" to see if they are. We don't find the word "rude" in the Bible, BUT Jesus DID say, "Do unto others as you would have them do unto you".Now I'm sure these people who treat others disrespectfully, and like garbage,they wouldn't themselves want to be treated like that. So isn't that a form of NOT doing unto others as you would have them do unto you?So when someone has a lifestyle of being rude{cutting the line, then getting mad at you if you don't like it, blasting the car horn 1/8 of a second after the light changes,{and other forms of impatience}talking to someone,and the other person is standing right next to the one they're talking to, yet they snub you, looking at them, and they either turn their head the other way, or close their eyes to avoid looking at you, or what I experienced in New York, maybe a bike messenger cutting you off when walking, then if you speak out on that, they either give you the finger, laugh at you, or even circle around to want to fight you--holding the door for their "clique", but you're right behind them and they let it slam on you--I've had problems with rude people for years--this attitude that"because you're a stranger, you're not important enough to be courteous to"--no, the Bible doesn't mention the word "rude" that I know of, BUT because this attitude of disrespect to others is a form of selfishness, and because they're not doing unto others as they would have them do unto them, if I were to answer that question, I would say rudeness is a sin.{"Because of the increase in inequity, the love of the greater number will wax cold".}