Martin Luther, from his Commentary on Galatians:
We who are born of the Gospel, and live in Christ, and rejoice in our inheritance, have Ishmael for our enemy. The children of the Law will always persecute the children of the Gospel. This is our daily experience. Our opponents tell us that everything was at peace before the Gospel was revived by us. Since then the whole world has been upset. People blame us and the Gospel for everything, for the disobedience of subjects to their rulers, for wars, plagues, and famines, for revolutions, and every other evil that can be imagined. No wonder our opponents think they are doing God a favor by hating and persecuting us. Ishmael will persecute Isaac.
Our opponents blame our doctrine for the present turmoil. But ours is a doctrine of grace and peace. It does not stir up trouble. Trouble starts when the people, the nations and their rulers of the earth rage and take counsel together against the Lord, and against His anointed. (Psalm 2.) But all their counsels shall be brought to naught. He that sitteth in the heavens shall laugh: the Lord shall have them in derision. (Psalm 2:4.) Let them cry out against us as much as they like. We know that they are the cause of all their own troubles.
As long as we preach Christ and confess Him to be our Savior, we must be content to be called vicious trouble makers. These that have turned the world upside down are come hither also; and these all do contrary to the decrees of Caesar, so said the Jews of Paul and Silas. (Acts 17:6, 7.) Of Paul they said: We have found this man a pestilent fellow, and a mover of sedition among all the Jews throughout the world, and a ringleader of the sect of the Nazarenes. The Gentiles uttered similar complaints: These men do exceedingly trouble our city.