“atheism – (from Greek a theos, ‘not god’) The denial of the existence of any god or supernatural being.”
The OXFORD WORLD ENCYCLOPEDIA 2003 Edition.
Occasionally I have come across the claim that Rudolf Steiner was an atheist in the 1880’s and 1890’s, before he founded Anthroposophy. By the above, the standard definition, I think it is clear that Steiner never an “atheist”. Steiner himself claimed that in the 1880’s and 1890’s he was anti-clerical, not anti-spirit, and his objection was to salvation from without and not to the basic existence of a spiritual world. As a self-professed idealistic philosopher during this time, he would have to believe in some form of a “spiritual” world, almost by definition. A critical review of his writing from that time period does not, to my knowledge, find evidence to contradict this. Clericalism and Anti-Clericalism were significant trends in Austria during that time, and I do not think that every person who was Anti-Clerical was pro-atheism, especially since many who were Anti-Clerical were Protestant ministers.