Sievers was born in 1905 in Hildesheim in the Province of Hanover (now in Lower Saxony), the son of a Protestant church musician. It is reported that he was musically gifted, that he played the harpsichord, organ, and piano, and loved German baroque music. He was expelled from school for being active in the Deutschvölkischer Schutz und Trutzbund and went on to study history, philosophy, and religious studies at Stuttgart's Technical University while working as a salesman.