James 5:1

1Go to now. They are mistaken, as I think, who consider that James here exhorts the rich to repentance. It seems to me to be a simple denunciation of God’s judgment, by which he meant to terrify them without giving them any hope of pardon; for all that he says tends only to despair. He, therefore, does not address them in order to invite them to repentance; but, on the contrary, he has a regard to the faithful, that they, hearing of the miserable and of the rich, might not envy their fortune, and also that knowing that God would be the avenger of the wrongs they suffered, they might with a calm and resigned mind bear them. (136)

But he does not speak of the rich indiscriminately, but of those who, being immersed in pleasures and inflated with pride, thought of nothing but of the world, and who, like inexhaustible gulfs, devoured everything; for they, by their tyranny, oppressed others, as it appears from the whole passage.

Weep and howl, or, Lament, howling. Repentance has indeed its weeping, but being mixed with consolation, it does not proceed to howling. Then James intimates that the heaviness of God’s vengeance will be so horrible and severe on the rich, that they will be constrained to break forth into howling, as though he had said briefly to them, “Woe to you!” But it is a prophetic mode of speaking: the ungodly have the punishment which awaits them set before them, and they are represented as already enduring it. As, then, they were now flattering themselves, and promising to themselves that the prosperity in which they thought themselves happy would be perpetual, he declared that the most grievous miseries were nigh at hand.

Besides, it was not unusual, in addresses to Christians, to address unbelievers. Indeed, Paul expressly says, “What have I to do to judge them that are without?”

That there were rich men professing the gospel at that time, is evident from James 1:10.