James continues the assault on the position of his interlocutor, this time pressing his point with a question. In verses 18-19 he countered the idea that faith and works can be separated, as though some people have faith, while others have works. The two cannot be separated: such “faith” is not faith at all, but simply knowledge about God rather than true reliance on God (see Moo, 107). This verse now serves as an introduction to a new phase in his argument: James will prove his point using Scripture, specifically, the examples of Abraham and Rahab (vv. 21-25).
“Do you want to be shown…?” (Theleis de gnōnai) is the first of three rhetorical questions in this section. James also will introduce the Abraham and Rahab examples with questions (vv. 21, 25). Gnosis typically means “to know” but here has the sense of “to be shown”. “You senseless (or foolish) fellow” (ō anthrōpe kene) is direct address in the second person singular. Again, even though it is possible that James’s hearers had been exposed to a distorted form of Paul’s teaching, it is better to understand this rhetoric as directed against an imaginary debating partner: such rhetoric was commonly practised in the ancient world. James is not using harsh words against an actual person, of the kind he will shortly reprove (3:9-10; 4:11; cf. Matthew 5:22; see McKnight, 243).
The adjective kene literally means “empty,” though it is used metaphorically in many places in the New Testament, including James 4:5. Here, James may be addressing his “empty-headed” opponent. Most commentators, however, suggest that the term refers not simply to intellectual but also to moral deficiency (e.g Moo, 107; Davids, 126; Vlachos, 95). This fits the context well: the person without works is not simply lacking understanding, but is out of step with the generous mercy and goodness of God.
The last phrase drives home James’s point with a play on words: “that faith without works is barren?” (hoti hē pistis kōris tōv ergōn argē estin). The word for “barren” or “useless” (argē) is negatively related to the word for “works” (ergōn). It means “no-work”—that is, a faith without works does not work! It is useless, barren, unfruitful and unproductive; it will not produce the salvation and blessing for which one hopes.