MAybe a new expression should be created.Yep. Pretty much what I said. I will discuss actions with regards to morality, calling them "sins" just isn't appropriate outside of religious context.
It's not that the word "sin" appears in religious contexts; it's that, to many, and I would say, the majority, the word "sin" still today carries with it the religious meanings that I may want to avoid in certain discussions. The various actions you listed before are certainly morally reprehensible, but if I were to call them "sin" I would be invoking religious ideas (such as commandments from god) that tend to go along with the word that I would feel is unnecessary in certain conversations. I don't avoid using the word, I will use the word when appropriate, but I don't feel it can be used without giving the topic at hand a religious undertone. If I don't want to involve religious context in the conversation, the word "sin" is definitely something I'm going to avoid.