Will Gog's army destroy itself?

Yes — Ezekiel 38:21 says every man's sword will turn against his brother, a judgment pattern Yahweh has used at Sinai, against Midian in Gideon's day, and which later prophets apply to the final day of the LORD.

Yes — and it is not an accident or a novelty. It is a covenant-judgment pattern Yahweh has deployed since Sinai.

Ezekiel 38:21 reads:

"I will summon a sword against him on all my mountains, declares the Lord Yahweh. Every man's sword shall be against his brother." (Ezekiel 38:21)

The verb is important: Yahweh does not say "I will fight." He says קָרָא (qara, H7121) — "I will summon" or "I will call." RSVP language. The army Gog assembled turns on itself at Yahweh's call. The pair חֶרֶב + אָח (cherev + ach, "sword" + "brother," H2719 + H251) is the canonical formula for coalition self-destruction, and it appears in a chain across the whole canon.

At Sinai, when Israel worshipped the golden calf, Yahweh sent the Levites through the camp with the command: "each man kill his brother, his companion, and his neighbor" (Exodus 32:27). That was the paradigm — Yahweh using an army against itself as a purging judgment.

Gideon's battle against Midian is the closest structural parallel. In Judges 7:22, Yahweh "set" (sim, H7760) the sword among the Midianites:

"Yahweh set every man's sword against his companion throughout all the camp." (Judges 7:22)

Israel did not fight. The coalition collapsed inward. Gideon's three hundred men blew trumpets and held torches; Yahweh did the rest. Ezekiel 38:21 applies the Gideon principle at eschatological scale. Israel is silent throughout the Gog oracle. The sword is not theirs.

Two later prophets carried the formula forward. Haggai 2:22, addressing "the thrones of kingdoms," promises that Yahweh "will overthrow the throne of kingdoms... and the horses and their riders shall go down, every one by the sword of his brother." Zechariah 14:13, in the final day-of-Yahweh scene, closes the chain: "a great panic from Yahweh shall fall on them, so that each will seize the hand of another, and the hand of the one will be raised against the hand of the other."

Sinai → Gideon → Gog → Haggai → Zechariah. Each time: Yahweh summons, the enemy implodes, Israel watches. The Gog war is not unprecedented. It is the eschatological climax of a pattern the canon has been building since the desert.

Read the full study on the Gog war