Sin exists only for people who are on the Way. Sin is what puts man to sleep when he has already decided to awaken.
(G. I. Gurdjieff)
Walking the Way can at times be an incredibly liberating down-hill journey, while at times it can be quite an uphill struggle. Programs have to be over-ridden, fears have to be faced and desires suppressed. If you think that walking the Way is simply always going with the flow, you are most likely mistaken.
"Sin" is easy to define when you are a spiritual traveler: it is a missed step along the Way. Missing the beat is tragic from one perspective, yet it is a trifle from another. Every moment is a new priceless opportunity to connect with the Way, so what exactly should we regret or worry about. Just get lost in the holy Now and let the sin of the past be history.
Since always maintaining the internal balance to be prepared for the holy Now can be hard work indeed, the temptation to just let go and fall back into the state of slumber is unfortunately very real. It can be the love for money or power, the cravings for sex, drugs or alcohol. Commit the"sin" of being disconnected and then observe how much work it is to get back onto the Way. There comes a day when you are unwilling to pay the price to be disconnected, but until that blessed day there is little you can do but battling for your freedom in an apparently endless yin and yang motion.
The word "sin" implies regret. Free yourself from this concept. What do you think gives you the will-power to try again harder next time around; what do you think gives you the staying power to do better this time? It is the mistakes of the past, they prepare you perfectly for comes your Way today. The Course in Miracles maintains, don't fear temptation but see it at what it is, another opportunity to choose again!
The Tree of Wisdom at the Garden of Eden is always in front of you, and the sound of the slithering snake is what keeps you awake. Why don't you use your new-found power to help a brother awake from his slumber today!