The symphony begins with a slow introduction which alternates between brass fanfares and responding strings playing the "Dresden Amen" (which later appeared in Wagner's Parsifal). The theme from the fanfare is used throughout the remainder of the first movement. The second movement takes the form of an upbeat dance built around a variant of the first movement theme. Mendelssohn then uses a much more restrained third movement, which features a theme played by strings and a small woodwind section at an andante tempo. Finally, the fourth movement, built almost exclusively around Luther's chorale "A MightyFortress is Our God," begins with a simple and direct introduction of the chorale by the flute. Various elements of the woodwind section, followed by strings and brass, are added until the full orchestra plays the chorale. Immediately, the tempo increases to allegro, as various instruments repeat the chorale theme until a final statement is given by the full orchestra with an accompanying trumpet fanfare.
Known familiarly as the "Reformation," Symphony No. 5 was actually composed before Symphonies 1, 2, 3 and 4, but its lack of success after two public performances around 1832 caused Mendelssohn to put it aside, and it wasn't published until after the composer's death in 1847.