A Mighty Fortress Is Our God stands as the battle hymn of the Reformation itself. Martin Luther wrote it in 1529, likely in response to the threat posed by the Catholic princes at the Diet of Speyer, where the evangelical states made their first formal Protest against the imperial edict.
Luther had read Psalm 46 closely: God is in the midst of her; she shall not be moved. God will help her at the dawn. The kingdoms may rage, the mountains shake, but God's city is safe. Luther married this promise to the political storm of his moment and asked: why are we afraid? Our God is already proven.
The hymn became the anthem of German Protestantism. Dietrich Bonhoeffer sang it in his cell. German soldiers sang it as they marched. It moved beyond church walls into the bloodstream of a people who believed that God's refuge was their only real security, more solid than fortifications or princes.
The theology is simple and overwhelming: one little word shall fell him. Not our strategy, not our cunning, but the word of God.