Most scholars since World War Two have assumed that composer Felix Mendelssohn Bartholdy (1809-1847) maintained a strong attachment to Judaism throughout his lifetime. As these commentators have rightly noted, Mendelssohn was born Jewish and did not convert to Protestantism until age seven, his grandfather was the famous Jewish reformer and philosopher Moses Mendelssohn, and his music was banned by the Nazis, who clearly viewed him as a Jew.

Such facts tell only part of the story, however. Through a mix of cultural analysis, biographical study, and a close examination of the libretto...