We commonly speak of three enemies that are both Christ’s and ours: world, flesh, and devil, which we feel and understand. In Rom. 8:7 St. Paul says: “For the mind that is set on the flesh is hostile to God.” Therefore God will also destroy it with its avarice and care, as he says 1 Cor. 6:13. Thus it is also certain that God will destroy the world. He has already ordered a fire in which it will be consumed and dissolved, as 2 Peter 3:10 tells us. In like manner He has also already sentenced and condemned the devil to eternal fire in hell, for he is God’s worst and chief enemy, who instigates every adversity and evil against God’s kingdom with lies and murder, also with terror, despair, and unbelief. God has these three foes, all of whom act and contend against Him. He in turn fights against them and arrays His whole kingdom solely against them. With His Word, Sacrament, and Spirit He holds the flesh in check. With these He also repels the devil and his venomous suggestions and all sorts of temptations, and also the world with its raging.

Martin Luther, Luther’s Works, Vol. 28: 1 Corinthians 7, 1 Corinthians 15, Lectures on 1 Timothy, ed. Jaroslav Jan Pelikan, Hilton C. Oswald and Helmut T. Lehmann, 1 Co 15:26–27 (Saint Louis: Concordia Publishing House, 1999).