In Greek you can imply the answer to a question.
- If you use ou, the expected answer is yes.
- If you use mē, the expected answer is no.
In James 2:24, James uses mē. He's not asking "Can faith save him?" He's saying, "Such faith (= workless faith) can't save him, can it?" What James is condemning is a faith that does not go beyond verbal profession. James, as much as Paul, roots a person's justification in their faith. As Calvin put it, "As Paul contends that we are justified apart from the help of works, so James does not allow those who lack good works to be reckoned righteous." The claim to be a Christian, if it is an authentic claim, will show itself in a new life obeying God, imitating Christ, and loving our brothers and sisters. Without such authentication, the claim is bogus.