The hymn became the anthem of Lutheran identity and then escaped denominational bounds altogether. Bach built his cantata Ein feste Burg on it and harmonized the melody in versions organists have played ever since. Mendelssohn wove the chorale through the finale of his Reformation Symphony, Meyerbeer threaded it through an opera, and Wagner, Raff and others quoted it as the instantly legible sound of German Protestantism, while Debussy quoted it hostilely in wartime.
English speaking congregations received it through dozens of translations, of which two dominate, Thomas Carlyle's A safe stronghold our God is still and Frederick Henry Hedge's 1853 A mighty fortress is our God, a bulwark never failing, the version most North American hymnals print. It is sung every Reformation Day, at church anniversaries and state occasions in Lutheran countries, and it is carved into the stone of the Luther memorials, including the tower of the Castle Church at Wittenberg, whose ring bears the first line in letters visible across the town. The hymn's afterlife has its shadows, it was conscripted into nationalist causes Luther could not have imagined, and postwar German Protestantism has handled its martial confidence with care, but the chorale itself has outlasted every use made of it, still doing its first job, giving a congregation one voice.