I like this sin or not sin concept. The paper I work for used to have an ethics column wherein a business dilemma was described each week, and the best answers were published the next week along with the next ethical conundrum. It was amazing how most readers opted for ethical response, but in so many different ways so that the least harm was done. It gave me great faith in humanity's ability to discern between right and wrong, if not our actual choices between them.
I've read those kinds of columns, too, and always enjoy the exercise of logic and ethical standards.
But it brings up a bigger question What is the difference between ethical behavior and sinless behavior? Isn't ethical behavior the honest and fair living-out of an agreement, whether that agreement is a law, a contract, a decision reached mutually? But isn't holiness (gotta use that word) the living-out of love?
If I live up to the teeniest part of a promise I make to you, no matter how it inconveniences me, then I'm being ethical. But note that I can resent it like hell, and complain about it to everybody else I know, and even maybe point out to you what a complete hero I'm being by honoring my commitment. My ethics would therefore have no grace, but they would still be very high.
But if I live up to the truth that God teaches me, that you and I are BOTH children of God, that we have equal value in His Eyes, both of us being totally "Crucifixion-worthy, then I am still rigorously honest in our hypothetical agreement, but I do it sweetly, at least on the outside, and better still, sweetly on the inside, never minding the effort, "offering up" my own prideful discomfort and giving up my desire for pats and praise.
So, not taking the mayo can be ethical (I wouldn't take another's calculated profit margin for my own ends) or it can be holy (not only would I not reduce the restaurant's profit margin, but I wouldn't give myself an over-comfortable life, I would keep it simple.)
Right? I am thinking out loud here. I have more examples to come, I am suddenly fascinated by how I can serve the Lord in my everyday actions by omission of previously selfish behavior.
In the meantime, please read my old "Ugly Pants" post, written, terrifyingly, nearly two years ago (I surely thought I would be holier by now...)