Sin is not a bad word
The concept of sin is often derided in modern society, especially by mystics and magicians, as irrelevent or antiquated. The reasons given generally include the idea that sin is only relevant in a guilt-based medieval form of Catholicism or in ignorant big-tend Bible-thumping. The fact is, however, that sin is a spiritual reality with a great deal of modern relevance, when properly understood.
We may profitably define sin as “any thought or action which tends to downplay our relationship with the Divine.” Running with that premise, it’s easy to see how sin relates to spirituality of any sort. In some systems, such as Judaism and orthodox Buddhism, we are given a list of rules to follow which will generally keep us away from sinning. In some other systems, however, like Christian mysticism and Zen Buddhism, emphasis is placed not on avoiding sinful actions, but instead on encouraging holy actions in a more generalized way.
Neither of these approaches is wrong; instead, they are best used together. The Buddhist Eightfold Path, the Ten Commandments, and similar lists, are useful guides but they are not universally relevant as there are many “gray area” situations in life. Thus, rulebook-style ethics are most useful when put into practice under the guidance of an overarching sense of Buddhist compassion or Christian love (or some similar idea, like the preaching of the Hebrew prophet Isaiah). Buddha took on students from every socio-religious caste in India, while Jesus emphasized that helping those in need took priority over even the Sabbath (or, in a sense, was a more perfect expression of the Sabbath).
Once again, it is a balance between the discipline of “the rules” and the laxity of “doing what needs to be done”.