Himmler was interested in mysticism and the occult from an early age. He tied this interest into his racist philosophy, looking for proof of Aryan and Nordic racial superiority from ancient times. He promoted a cult of ancestor worship, particularly among members of the SS, as a way to keep the race pure and provide immortality to the nation. Viewing the SS as an "order" along the lines of the Teutonic Knights, he had them take over the Church of the Teutonic Order in Vienna in 1939.
Source: Wikipedia