James uses very pointed language, because you and I all tend to have these little social sins that we like to stick away in a category and say that they are not really as bad as real moral faults. And James wants us to understand that even thoughts, unexpressed prejudice, are contempt. Grudges, wrong anger, hatred—those things make us transgressors of God's law. He wants us to understand how important sins of the heart and attitude are, so that we will not cherish them, gloss over them, explain them away, or ignore them. But, in fact, being convicted by the law, we will deal with them.1
Joseph A. Pipa
9 But if you show partiality, you are committing sin and are convicted by the law as transgressors.