In his magnum opus, Scholem reconstructs a life story that had a unique impact on Jewish history. The millennia-long history of the Jewish religion, mysticism, and Kabbalah serves as the backdrop against which the story of Sabbatai Zvi (1626-1676) unfolds. Sabbatai Zvi is the first fundamental study of heresy and apostasy in Judaism. Scholem dates the beginning of modern Jewish history with Sabbatianism. However, the history of Sabbatianism remained in the shadow of official Jewish historiography for centuries. Scholem's book fills this significant historical gap. Furthermore, it is a standard work in religious studies, as Scholem compares Jewish and Christian fundamental concepts in his investigation while also highlighting their differences.