This is a sequel to my earlier post:
How do we harmonize Paul and James on justification? The short answer is that Paul and James are talking about two different things.
James is concerned with the nature of saving faith. Between dead faith and living faith. Living faith is a lived faith. Living out what you profess with your lips. Enacted faith.
Living faith is a persevering faith. The walk of faith is for marathon runners, not sprinters. The true test is not how you begin, but how you end.
And even if we stick with the terminology of "justification"–which can be misleading (see my prior post)–James isn't saying that justification includes works. Rather, he's saying faith includes works–not in the sense that faith is partly a work, but that living faith results in good works.
By contrast, Paul uses "justification" to mean righteousness is a divine gift. We have no righteousness of our own. Rather, we have the righteousness of Christ. An ascriptive status rather than an achieved status. Indeed, in spite of what we are like, on our own terms. Like the son of a king, who is a prince, not because of something he did, but because of something he was born into.
Paul usage is idiosyncratic. He redefines the "justification" word-group for his own purposes. And every writer has that prerogative. Writers aren't bound by prior usage. They are free to invest old words with new meanings. James doesn't use "justification" in that specialized sense. So there's no contradiction. But due to the influence of Pauline theology, his innovative usage became the dominant usage, which is confusing if read back into James.
And Paul agrees with James on the nature of saving faith. But Paul is concerned with something different. He's wrestling with a theological dilemma. How can a holy God forgive sinners? Sinners aren't good enough to merit salvation on the basis of their own goodness.
Indeed, their situation is worse than that. It's a duty of a righteous God to punish the unrighteous, not to forgive them. What makes a just God just is that he exacts retribution on the unjust. To acquit the guilty is the mark of an unjust judge. So how can God justly forgive the unjust?
Paul's solution is penal substitution. The vicarious atonement of Christ.
And justification by faith mirrors vicarious atonement. To place your faith in another is to resign faith in yourself. To hope in another abandons hope in yourself.