Every one brought assistance to his neighbor. What now follows agrees well with what goes before, if you connect this verse with the last clause of the former verse, "They drew near, they were assembled, every one assisted his neighbor;" so that the meaning is, "Although the islands saw and knew my works, so that they trembled at them, yet they assembled in crowds to make a league among themselves." Why? That they might encourage each other to frame new gods, and might confirm each other more and more in their blindness. He therefore aggravates the guilt of the Gentiles by saying, that "every one assisted his neighbor;" and indeed whoever shall make careful inquiry will find that this is the source of all superstitions, that men by mutual consent darken the light brought to them from heaven. But although the Lord here expostulates with idolaters, yet he does it for the sake of the Jews, that they may not fall into the impiety of the Gentiles, or permit themselves to be turned aside from God and from sincere faith. [1] On this account he brings forward the ingratitude of the Gentiles, that the Jews may not imitate it, but may remain steadfast in the true worship of God. And said to his neighbor, Be courageous. Here we see, as in a mirror, how great is the wickedness of men, who profit nothing by considering the works of God, and are even rendered more rebellious, and harden themselves more and more; for they choose of their own accord to be blind, and to shut their eyes against the clearest light, rather than to behold God who manifests himself before their eyes. To blindness is added rage, in consequence of which they rise up against God, and do not hesitate to wage war with him for defending their superstitions; so that this vice is not idol worship but idol madness. Isaiah describes this madness by saying, "Be bold, act courageously;" for he means that men have entered into a base conspiracy, by which they naturally encourage and inflame each other to the worship of idols, and to drive away the fear of God which his power might have led them to entertain.

Footnotes

1 - "De la droite fiance en luy." "From proper confidence in him."

They helped every one his neighbor - The idolatrous nations. The idea is, that they formed confederations to strengthen each other, and to oppose him whom God had raised up to subdue them. The prophet describes a state of general consternation existing among them, when they supposed that all was in danger, and that their security consisted only in confederation; in increased attention to their religion; in repairing their idols and making new ones, and in conciliating the favor and securing the aid of heir gods It was natural for them to suppose that the calamities which were coming upon them by the invasion of Cyrus were the judgments of their gods, for some neglect, or some prevailing crimes, and that their favor could be secured only by a more diligent attention to their service, and by forming new images and establishing them in the proper places of worship. The prophet, therefore, describes in a graphic manner, the consternation, the alarm, and the haste, everywhere apparent among them, in attempting to conciliate the favor of their idols, and to encourage each other. Nothing is more common, than for people, when they are in danger, to give great attention to religion, though they may greatly neglect or despise it when they are in safety. Men fly to temples and churches and altars in the times of plague and the pestilence; and as regularly flee from them when the calamity is overpast.
Be of good courage - Margin, as Hebrew, 'Be strong.' The sense is, Do not be alarmed at the invasion of Cyrus. Make new images, set them up in the temples, show unusual zeal in religion, and the favor of the gods may be secured, and the dangers be averted. This is to be understood as the language of the idolatrous nations, among whom Cyrus, under the direction of Yahweh, was carrying his conquests and spreading desolation.

They helped every one his neighbour; and [every one] said to his brother, (h) Be of good courage.
(h) He notes the obstinacy of the idolaters to maintain their superstitions.

They helped everyone his neighbour,.... By advice and counsel, by the best arguments they could make use of, to withstand the new religion, and defend the old one; to prevent the embracing the one, and relinquishing the other:
and everyone said to his brother, be of good courage: or, "be strong" (m); they strengthened one another's hands in their idolatrous worship, encouraged each other to oppose the prevailing doctrine; urging, that the craft of some was in danger, and the religion of them all at stake, and their gods like to fall into contempt. An instance of this may be seen in Demetrius the craftsman at Ephesus, when the Gospel mightily prevailed there, who stirred up the workmen of the same craft with himself and the like, suggesting the loss of their business, and the dishonour reflected on their goddess Diana, should the apostle go on as he did; by which we may judge how it was, more or less, in other parts of the world; see Acts 19:20.
(m) "fortis esto, vel sis strenuus", Vatablus.

Be of good courage--Be not alarmed because of Cyrus, but make new images to secure the favor of the gods against him.