I think that, as a rule of thumb, for the Christian, sin is an outdated concept. Just as the unbeliever should be aware that the Creator will have to be reckoned with whether they like it or not, their concern should also include answering to the Creator for the sinful nature inherent in human nature (because of the human inability to be perfect,...fallibility, it's not always that somebody has intentions of being evil, many people really do have good intentions, but fallibility remains and will always be part of the human condition, in fact, it is what makes us human). Sin is only a broad term for imperfection (which is ANYTHING that can make us incompatible with God,...outlined in the 10 commandments). The classification of something as a sin is performed without any regard to the resulting consequences, suffering, pain and misery that is caused. Besides developing a personal relationship with the Creator and recieving eternal life, the Christian should learn to have a HIGH regard for the resulting consequences, James 4:9 "...turn your laughter to tears and your joy to dejection" (Job did, Genesis 18, his heart was sorely vexed).
Sin is not very clearly defined and there is no universal agreement on what constiutes one. A police officer will not arrest you for one or give you a ticket for one, but sin is something we impose on each other in the name of God (for the sake of our bruised ego, we unintentionally need to feel better about ourselves and, in effect, call the wrath of God upon each other, not very nice, is it?).
I know that it CAN BE USEFUL to chastize each other and teach each other the error of our ways, but I think it does much more harm to each other's personal relationship, devotion and understanding of accountability to The Lord (let alone fosters in ourselves a 'primadonna' feeling of being a judgemental control freak). In learning respect (GENUINE love) for the creation made in The Lord's image and likeness, we should realize that our brethren have a PERSONAL relationship to covet and that The Lord wants His spirit to yearn jealously (James 4:5). It is only my personal opinion, but I think The Lord would like us to be more instrumental in preserving (nurturing) His personal relationship to the brethren and not encourage our brethren to also be accountable to us, for it is not only my brethren's personal relationship, it is my Lord's also (He is a jealous God).
I know it seems as though it is a violation of the spiritual rules for a woman to have short hair (maybe it is, maybe when you get to heaven, The Lord will tell you to grow your hair longer and the angels will give you dirty looks, KIDDING). As long as God doesn't have a police force (although there are many vigilantes), it's unlikely you will ever get a ticket for that (I think short hair is very attractive and it's only the puffed up Holier than thou 'equality with God' Phillipians 2:6 crowd that has a problem with it). If by some chance it is not spiritually proper, you can count on me to be your advocate, just as Jesus is ours before The Father (I'll even pay the ticket).
Now that we have spent some time getting to know God better (since salvation), we should no longer be nourished with the MILK of the Word, but solid food, and "solid food is for the mature" because we've learned to DISTINGUISH (not DECLARE what is SIN) between GOOD and EVIL. Whenever we plan to do something GOOD but because of time constraints or laziness, we CHANGE those plans even slightly (take short cuts), that GOOD (complete and perfect good) becomes EVIL (because it prevents the absolute of GOOD). REGARDLESS of our justification for the shortcuts, PURE goodness was still prevented, and this 'prevention' is what matters to The Lord because there are always consequences that must be suffered by someone. So, that's it, in The Lord's eyes, something is either good or evil, there is no middle ground (in The Lord, there is no shadow or variation DUE TO CHANGE,...either/or).