“And in Ps. 120:7 we read: ‘I am for peace; but when I speak, they are for war!’
This does not happen when the devil preaches to his own. His doctrine is easily swallowed, for it is comprehensible to reason. But here, where I am peaceful and do not seek war but strive to bring salvation to all the world and preach the Gospel, war is already at hand. The devil senses that the people are being snatched from his toils and trap and are being led into the kingdom of the Lord Christ. Therefore he agitates whomever he can, and he himself wakes up and becomes mad and furious. Thus the peaceful must have a reputation as disturbers of the peace; they must bear the blame for creating discord. But those who break the peace and start the controversy boast that they are lovers of peace. Let it go! The devil rages this way to intimidate people, lest they adhere to the Gospel. Thus he slanders Christ, His followers, and the apostles as instigators of strife and discord.
This complaint is lodged against the apostle Paul in the Book of Acts (24:5), where we read: ‘We have found this man a pestilent fellow, an agitator among all the Jews throughout the world.’ And Christ Himself declares (Matt. 10:34): ‘I have not come to bring peace on earth, but a sword. I will set a son against the father and a father against the son.’ The text offers us consolation against this offense and against the idle talk and the bragging which our adversaries now direct against us” (Luther’s Works, v. 23, p. 291-292).