When people ask, “How is James using the word justified?” Or “faith?” etc, they are inadvertantly missing the point.  The question is not, “How did James use the word?” but “How did James and all his intended readers use the word?”

James was writing a pastoral letter to warn and encourage.  It would make no sense whatsoever if he decided to use words in a highly idiosyncratic way.  No, he used the common language of his audience.  Everyone in the church spoke that way about justification and faith.