When we use the phrase "like sin," we usually mean something that is bad, immoral, or shameful. Fortunately, there are many synonyms that can convey similar meanings. For example, we might say something is "like a crime," "like a vice," or "like an offense." Other options include "like a transgression," "like a misdeed," or "like a wrongdoing." Alternatively, we might use more colorful expressions, such as "like the devil himself," "like a stain on the soul," or "like a mark of disgrace." No matter which synonym we choose, the overall message is clear: the thing being described is something to be avoided or condemned.