What is sin?

One popular philosophy states that we should do whatever we want as long as it does not hurt anyone else. However, along the lines of what I was saying in this week’s religious section, what about hurting ourselves? I define sin as searching for happiness in the wrong places. We all want to be happy but rarely do we make decisions that help us attain or obtain that happiness. If we do whatever we want as long as no one gets hurt, we can easily justify. Perhaps we want to have a relationship with someone who is already married. And we rationalize it by saying that their marriage is already not happy. However, if we pursue someone who is married, we shortchange ourselves. Therefore, the philosophy of doing what we want as long as it does not hurt others seems suspect.