As he did before ( James 2:2-4), James provided a concrete situation to illustrate his point ( James 2:15-16). He envisioned a situation that may very well have taken place in his church in Jerusalem where there were many poor saints ( Romans 15:25-31; 1 Corinthians 16:3). All the people in the illustration seem to be genuine Christians in view of the terms James used to describe them (cf. "brethren" in James 1:2; James 2:1; James 2:14; James 3:1). The situation he described highlights the absurdity of claiming vital faith (i.e, that one is putting his faith into practice) but at the same time not working (i.e, not obeying the Word of God; cf. 1 John 3:17-18). A benediction cannot save a starving man from death; only bread can do that. [source][source][source]
One Greek scholar paraphrased James 2:14-17 as follows. [source][source][source]
"What good does it do, my Christian brothers, if someone among you says he has faith and yet does not act on that faith? Faith certainly cannot preserve his life, can it? It would be the same thing as if one of you spoke to some Christian brother or sister who was destitute of the necessities of life and you said, "Go home peacefully and get warmed and filled." But if you did not give them the very things they needed for bodily life, what good would it do? Would their lives be saved by your confident words? In the same way when faith stands all by itself, because you fail to act on it, your inactive faith is as dead as your useless words to your destitute Christian brother. It has no life-preserving power at all!" [1][source]