Question: "What does it mean that "no weapon formed against you shall prosper" (Isaiah 54:17)?"
Answer: In Isaiah 54:11–17, the prophet Isaiah delivers a message from God about the restoration of Jerusalem after its destruction by the Babylonians. The people would be in chaos and confusion, but the Lord promises a future day when the city will be more glorious than ever. God’s people will return to their land and live there without fear of further devastation: “‘No weapon formed against you shall prosper, And every tongue which rises against you in judgment You shall condemn. This is the heritage of the servants of the LORD, And their righteousness is from Me,’ Says the LORD” (verse 17, NKJV).
In saying that “no weapon formed against you shall prosper,” God promises the people of Jerusalem that no enemy will be able to produce successful weapons against them. The word prosper here means “succeed.” The previous verse gives context: “See, it is I who created the blacksmith who fans the coals into flame and forges a weapon fit for its work. And it is I who have created the destroyer to wreak havoc” (Isaiah 54:16). In other words, God is in charge. He created the one who creates the weapons, and He will see to it that whatever weapons are wielded by Israel’s enemies would be ineffective against them. This promise will see its ultimate fulfillment in the millennial kingdom of Christ (see Isaiah 51).
The promise to Israel is often applied to God’s children today, as we deal with spiritual enemies. No matter what the devil devises to throw at us, in the end it will fail because God is the sovereign ruler of our destiny. He gives us the shield of faith, “with which you can extinguish all the flaming arrows of the evil one” (Ephesians 6:16). The Good News Translation phrases Isaiah 54:17 like this: “‘But no weapon will be able to hurt you; you will have an answer for all who accuse you. I will defend my servants and give them victory.’ The LORD has spoken.”
The primary theme the Lord wants to communicate in this passage is that God is our salvation. Even when bad things happen to us—when we feel defeated and crushed by our enemies—we can trust and not be afraid: “God is our shelter and strength, always ready to help in times of trouble. So we will not be afraid, even if the earth is shaken and mountains fall into the ocean depths; even if the seas roar and rage, and the hills are shaken by the violence” (Psalm 46:1–3, GNB). Even if our cities lie in ruins, a deadly disease wreaks havoc in the world, the economy fails, and we lose our job, the Lord Almighty is with us, and He will save us: “God is in that city, and it will never be destroyed; at early dawn he will come to its aid. Nations are terrified, kingdoms are shaken; God thunders, and the earth dissolves. The LORD Almighty is with us; the God of Jacob is our refuge” (Psalm 46:5–7, GNB).
A weapon is anything designed to inflict harm. In 2 Corinthians 10:4, the apostle Paul tells us that we have been given tools to fight against our enemy, but our weapons are not ordinary armaments: “The weapons we fight with are not the weapons of the world. On the contrary, they have divine power to demolish strongholds.” Often, the enemy hits us with spiritual strongholds of confusion, depression, anger, anxiety, fear, temptation, and loneliness. But the Lord has given us His Word as our sword and faith as our shield (Proverbs 30:5; Hebrews 4:12), and we have His spiritual armor to protect us (Ephesians 6:10–18).
God is in command. He controls both those who make weapons and those who use them. The battle is not ours, but the Lord’s (2 Chronicles 20:15; 1 Samuel 17:47). He has already won the contest. Through Jesus Christ, He has defeated the final enemy, who is death, and purchased for us eternal life (2 Timothy 1:10; see also Isaiah 25:8; Hebrews 2:14; Revelation 1:18). The Lord will protect and uphold His children, no matter what we face, and help us through to the final victory (Isaiah 41:10). As God’s people, we can be confident in the Lord’s ultimate triumph over every enemy. In Isaiah’s time, as in all of history, and in the future in its fullest sense, every child of God can say, “No weapon formed against me shall prosper!”