John Calvin on Joel 3:17

This is a confirmation of the preceding doctrine, ye shall know, he says, that I am your God. The Prophet intimates that the favor of God had been so hidden during the afflictions of the people, that they could not but think that they were forsaken by God. His word ought indeed to be sufficient for us in the greatest evils; for though God may cast us into the deepest gulfs, yet when he shines upon us by his word, it ought to be a consolation abundantly available to sustain our souls. But yet, unless God really appears, we are confounded, and ask where is his power. For this reason the Prophet now says, that the faithful shall at length know, that is, really know him as their God.

There is a twofold knowledge, — the knowledge of faith, received from his word, — and the knowledge of experience, as we say, derived from actual enjoyment. The faithful ever acknowledge that salvation is laid up for them in God; but sometimes they stagger and suffer grievous torments in their minds, and are tossed here and there. However it may be with them, they certainly do not by actual enjoyment know God to be their Father. The Prophet therefore now treats of real knowledge, when he says, that they shall know that they have a God, — how are they to know this? By experience. Now this passage teaches us, that though God should not put forth his hand manifestly to help us, we ought yet to entertain good hope of his favor; for the Prophet spoke for this end, — that the godly might, before the event or the accomplishment of the prophecy should come, look to God and cast on him all their cares. Then the faithful, before they had real knowledge, knew God to be their Father, and hence hesitated not to flee to him though what the Prophet testified had not yet been visibly accomplished.

Dwelling in Zion, the mountain of my holiness: This has been designedly added, that the faithful might know, that God made not a covenant in vain with Abraham, that mount Zion had not in vain been chosen, that they might there call on God; for we must have our attention called to the promises, otherwise all doctrine will become frigid. Now we know that all the promises have been founded on a covenant, that is, because God had adopted the people, and afterwards deposited his covenant in the hand of David, and then he designated mount Zion as his sanctuary. Since, then, all the promises flow from this fountain, it was necessary to call the attention of the Jews to the covenant: and this is the reason why the Prophet says now that God dwells in Zion; for otherwise this doctrine would no doubt only lead to superstition. God, indeed, we know, cannot be included within the circumference of any place, much less could he be confined to the narrow limits of the temple; but he dwelt on mount Zion on account of his own law, because he made a covenant with Abraham, and afterwards with David.

It then follows, And Jerusalem shall be holy, and aliens shall not pass through it any more. While he declares that Jerusalem shall be holy, he exempts it at the same time from profanation. We know that it is a common mode of speaking in Scripture, and what often occurs, that God’s heritage is holy, and also, that they profaned it. Hence, when the people were exposed as a prey to the pleasure of their enemies, the heritage of God became forsaken and polluted, profane men trod Jerusalem as it were under foot. But now the Prophet exempts the holy city from this pollution, as though he said, “The Lord will not allow his people to be thus miserably harassed, and will show that this city has been chosen by him, and that he has in it his dwelling. Aliens then shall no more pass through it — Why? For it is first the holy city of God, and then, of his Church.

But as this promise extends to the whole kingdom of Christ, God doubtless makes here a general promise, that he will be the protector of his Church, that it may not be subject to the will of enemies; and yet we see that it often happens otherwise. But this ought to be imputed to our sins, for we make the breaches. God would, indeed be a wall and a rampart to us, as it is said elsewhere, (Isaiah 26:1;) but we betray his Church by our sins. Hence aliens occupy a place in it: Ye we see at this day; for Antichrist, as it has been foretold, has now for ages exercised dominion in God’s sanctuary. Since it is so, we ought to mourn at seeing God’s holy Church profaned. Let us yet know, that God will take care to gather his elect, and to cleanse them from every pollution and defilement. It follows —

Joel 3:18-19

18. And it shall come to pass in that day, that the mountains shall drop down new wine, and the hills shall flow with milk, and all the rivers of Judah shall flow with waters, and a fountain shall come forth of the house of the Lord, and shall water the valley of Shittim.

18. Et erit in die illa, stillabunt montes mustum, et colles decurrere facient lac; et omnes rivi Jehudah emittent aquas (hoc est, descendere facient,) et fons e domo Jehovae egredietur et irrigabit vallem Sittim.

19. Egypt shall be a desolation, and Edom shall be a desolate wilderness, for the violence against the children of Judah, because they have shed innocent blood in their land.

19. Aegyptus in solitudinem erit, et Edom in desertum solitudinis erit, propter vexationem filiorum Jehudah; quia fuderunt sanguinem innoxium (vel, purum) in terra sua (vel, ipsorum.)