Cover of If with all your hearts by Mendelssohn-Bartholdy (Boston: E. H. Wade, [n.d.]). Performing Arts Reading Room, Library of Congress.
Felix Mendelssohn was born into a family of means and privilege. His intellect and aptitude for music were apparent at an early age; by the age of fourteen he had already demonstrated an astonishing facility for musical composition, composing over one hundred works, from small scale keyboard works to large scale operas and symphonies. But the apparent effortlessness with which Mendelssohn met continued successes (and enjoying that rarest of commodities extended to composers -- fame and recognition by the public during their lifetime) as well as the advantages afforded him due to his family's social standing belied a turbulence that would appear incongruous to the composer of vibrant, joyous works such as the Midsummer Night's Dream Overture and the Octet. The society and culture in which Mendelssohn worked and lived was rapidly evolving.
Born into a Protestant family of Jewish heritage, at a time when Jews were still largely marginalized in society, Mendelssohn's own life might aptly serve as a metaphor for the conflicting social attitudes of his era. His maternal grandfather, Daniel Itzig (1723-1799), worked within the status quo by serving as a banker to the royal court of Frederick the Great, eventually obtaining special privileges for his family and heirs -- that is, the same privileges enjoyed by other German (Christian) citizens. Mendelssohn's paternal grandfather, Moses Mendelssohn (1729-1786), is considered to be the preeminent Jewish philosopher of the German Enlightenment; as an objective observer of society, removed from the status quo, he called for religious tolerance towards Jews and for their full participation in German society.
Despite the pro-Jewish stance of the children of both Moses Mendelssohn and Daniel Itzig, the sober reality of the era was that practicing Judaism in late eighteenth century Germany substantially limited one's access to professional opportunities. While two of Moses's children retained the Jewish faith, two others converted to Catholicism, and the remaining two embraced Protestantism. Felix's father Abraham Mendelssohn (1776-1835) was one of the latter, although (tellingly enough) he and his wife Lea Salomon (1777-1842) did not officially convert until 1822.
In 1816, at the age of seven, Felix, along with his siblings, were baptized into the Protestant faith. At about this time, the family added the surname "Bartholdy" to their existing name (to become Mendelssohn Bartholdy). The addition of this surname, urged by Lea's brother Jakob Salomon (later Jakob Bartholdy, adopting the name of a family dairy farm) who had converted to Christianity in 1805, indicates the lengths to which even cultured, protected, monied, educated Jews felt constrained to conceal their heritage within an intolerant society.
While Felix Mendelssohn Bartholdy was raised and remained a practicing Lutheran throughout his life, and never received any religious instruction in Judaism, it would appear that he retained a substantial sense of his Jewish identity -- something of which he would have certainly been aware in his daily life as part of a family that had, by all indications, successfully assimilated into German (Prussian) culture, but who were nevertheless regularly subject to instances of anti-Semitism. Predictably, the very public nature of Mendelssohn's career proved the easiest target for anti-Semitic sentiments. It is revealing, however, that in the subjects of the two biblically-inspired oratorios produced in the last year of his life -- Elijah and Christus, reflecting, respectively, the Old Testament of his Jewish heritage and the New Testament of the Protestant faith adopted by his family -- may be discerned a rapprochement, or an attempt at such, between these two parts of his identity. Perhaps like his grandfather Moses before him, Mendelssohn was striving to reconcile issues of spirituality and religious tolerance within society, and within himself as well.