My pastor has unearthed some interesting nuances of language WRT that sort of scripture in recent months. In Hebrew (and likely Aramaic), the meaning of the phrase "I believe ..." meant that the speaker responds or is responding to that belief with some sort of action or change in their life. The Hebrew mindset of the day could not conceive of "belief" that led nowhere, as it were; in such a case, you do not "believe".
This, IMO, is what James is also arguing. In other words, Belief must have a visible, physical component - often called Works - that happens because one believes.
Wade.