Luther’s original melody for the chorale Ein’ Feste Burg ist Unser Gott possesses a vibrant, rhythmic character similar in style to the popular folk music of early 16th-century German lands. The melody was carefully crafted to pair with the naturally occurring poetic stresses of the hymn text. Over time, the asymmetrical rhythmic version of EIN’ FESTE BURG was replaced with an isometric setting of the tune. This study outlines the importance of Luther’s original composition, suggests a setting of the melody that preserves the essence of the original rhythm within a modern notational framework, and uses that model as a basis for analyzing the thematic development of the hymn tune in Philip Sparke’s Between the Two Rivers: Variations on Ein’ Feste Burg. The analysis identifies all unique appearances of thematic material derived from the seven phrases of the hymn. A musical analysis of Between the Two Rivers concludes that the isometric setting of EIN’ FESTE BURG was used in the composition of the work.