John Calvin Commentary Zechariah 2:5

"For I, saith Jehovah, will be unto her a wall of fire round about, and I will be the glory in the midst of her." — Zechariah 2:5 (ASV)

He confirms in this verse what I have just mentioned: that Jerusalem would be safe, even without any fortifications, for God alone would be sufficient for walls, towers, and fortresses. This is according to what is said by other Prophets: God will be to thee a wall and a fortress (Isaiah 26:1), and again, he will be to thee a stronghold. It is, therefore, a statement in accordance with other prophecies when Jehovah testifies that He would be a wall of fire. We indeed know that even though walls may be high and thick, enemies can scale them; but who will dare to throw himself into the fire? It is then as if God had spoken thus: “Though there will be no watchmen to defend Jerusalem, no soldiers to protect it, in short, no guardians whatever, yet I alone shall be sufficient; for I shall not only be a wall to keep off enemies, but I shall also be a fire to fill them with terror.”

He then adds, I will be for glory in the midst of her: as if He had said, “The real happiness of Jerusalem, within and without, will be in Me alone and in My favor. Within, in the midst of her, I will be for glory; I will adorn her with everything praiseworthy. When any fear arises from the assault of enemies, I will be to her a wall of fire. For though she will not excel in strongholds and towers, and be without walls and fortresses, and will thus be exposed to many evils, I shall yet strike all enemies with terror, so that they will be kept far off; and My Church will thus be preserved safe, though destitute of all human aid and without any defense.”

We now perceive, then, the Prophet's meaning to be this: that even though the Jews saw themselves as few in number, weak in strength, wretched, and despised, they still had reason to entertain hope.

For although few returned from exile, God was still able to increase the Church and make it a vast multitude. This was certain and decreed, for the vision showed that however unequal they were to their enemies, God was still sufficiently strong and powerful to defend them.

Furthermore, however destitute they were of all blessings, God was still rich enough to enrich them, provided they relied on the blessing He had promised. For He had pledged to make them happy and blessed within, and safe from enemies without.

Prayer:

Grant, Almighty God, that as we are surrounded on every side by many enemies, and as Satan never ceases to kindle the fury of many to be not only hostile to us but also to destroy and consume us—O grant that we may learn to raise our eyes to heaven and, trusting in Your protection, may boldly fight with patience, until what You once testified in this remarkable prophecy appears: that there are many smiths in Your hall and many hammers by which You break to pieces those horns which rise up to scatter us; and until at last, after having overcome all the devices of Satan, we shall reach that blessed rest provided for us by the blood of Your only begotten Son. Amen.