No, we don't. In order to sin, you have to transgress divine law. Since our deities don't give us laws, we can't possibly sin.
However, we do believe that we can err. We make mistakes, goof, choose unwisely, have bad discernment days - whatever you want to call it.
The ethical code that most of us try to live by involves harming no one, including ourselves, and interfering in no one else's choices. When we do either of these things, by accident, by choosing unwisely, or quite purposely in anger (we aren't perfect, after all) we generally try to make it up somehow. Usually, if we can, we try to apologize and repair whatever damage we did.
Because, unlike a group that has sin, we can't go to the Gods and say, "I'm sorry. Now please forgive me and make it all right." It's not the Gods we hurt, so they aren't interested in our repentance. We have to beg pardon from an actual person, who may not feel so kindly toward us right now. And that, I think, is much harder.
If we don't, the three-fold law comes into play. That is, anything you put out into the universe comes back to you three times. So if you put hurt out there, you get hurt back, only worse. Which gives me motivation, anyway.
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