But now it is a wondrous thing that Christ destroys the enemy and avenger by the strength that is ordained from the mouths of infants and sucklings. For the enemy and avenger is a strong and mighty spirit. He is the god and prince of the world, and under him he has a strong and well-established kingdom and many other spirits, each of whom is stronger than all the men on the earth. The infants and sucklings, on the other hand, are poor, weak human beings, caught in the enemy’s power. For through Adam’s fall and sin all men came into death and the devil’s tyranny. In such weakness and imprisonment, what can they ever accomplish against the enemy and the avenger? Infants and sucklings will offer little resistance and do little damage to these strong and mighty spirits and these great and powerful tyrants on earth, who ride in the devil’s service as his retinue and rage against Christ and His church—especially because they wield no sword but are supposed to fight only with their mouths. Why does He not send the heavenly spirits and princes, Gabriel, Michael, and other angels, who could stoutly resist the enemy and demolish him?
Answer: The Lord, our Ruler, did not want to use Gabriel or Michael for this, but He wanted to ordain strength from the mouths of infants and sucklings. For since the enemy’s iniquity is great and his anger violent, this Ruler takes pleasure and joy in making a fool of such a wicked, fierce, and proud spirit, and mocking him. In order to ordain this strength, He degrades Himself so profoundly and becomes a man, yes, even degrades Himself below all men, as it is written in Psalm 22:6: “I am a worm and no man; scorned by men, and despised by the people.” Therefore He goes about in poverty, as He Himself says, Matthew 8:20: “Foxes have holes, and birds of the air have nests; but the Son of Man has nowhere to lay His head.” In such physical weakness and poverty He attacks the enemy, lets Himself be put on the cross and killed, and by His cross and death He destroys the enemy and the avenger, as St. Paul says, Colossians 2:15: “He disarmed the principalities and powers and made a public example of them, triumphing over them in Him.”
Luther’s works, vol. 12: