Hi Netti-Netti and Seattlegal,
i guess the easiest place to start would be contrasting (some) Jewish ideas of sin with (some) Christian ones. Please understand that i'm going to be making generalizations for the purpose of discussion based on my understanding of the main themes of both religions and i apologize in advance for any unintentional offense.
Jewish thought, Adam and Eve notwithstanding, doesn't include a belief in “original sin,” and people are not thought to be “born sinners”. Rather, people are born with a “pure soul” and also with both an inclination toward “good,” and an inclination toward “evil.” (“Listen to the angels of your better nature,” our rabbi tells us.)
The Jewish idea of sin is also not based on the idea of punishment and reward, in this life or the afterlife. In contrast with modern formulations of “human rights,” Jews consider their relationship with G-d to be based in “human responsibilities.” We're expected to do our best with what we're given, to do “good” for the sake of doing good, and in fact there are some lines of thought that suggest that focusing on the idea of reward and punishment actually taints one's “good” with selfish motives.
i think there's a nice correlation here with your statement, Netti-Netti:
"I think it's about wrong attitude - namely, disrespect for the L-rd" because, Jewish thought recognizes both “crimes” (violations of human rights) and “sins,” (violations of “the obligation placed on us by virtue of the Divine command requiring us to behave in a way that befits the image of G-d in which we were made”).
Parashat VaYelekh - Dr. Meir Seidler
To answer your question more directly:
“Chet” is the often-quoted archery term meaning “missing the mark:” one tries to do good, but falls short or goes a bit astray. Here the sin is not so much “doing evil” as “missing” the opportunity to “do good.”
“Aveira” means “crossing the line,” a fully-conscious choice, and considered more grievous.
“Avon,” or “abomination,” most heinous of all, would include idolatry and murder.
Hope this opens a fruitful dialog.
night