Waldorf Mommy said: "Do you think Waldorf teachers would react in some negative way to a student who argues that a higher power doesn't exist?"
That's exactly what happened to my child in Waldorf high school. My son, a Dawkins fan, has homework assignments that demonstrate his teacher insisted that he hadn't "considered all the possibilities" when he discredited the intelligent design she was teaching his class. He was accused of being "closed-minded" in front of his class. His assignments are marked up with comments by his teacher that challenge science and PUSH intelligent design and his grade was lowered because he refused to accept intelligent design in his lessons.
That is what you will find in Waldorf... teachers who push Anthroposophy at every opportunity (as Steiner intended) - expressing to children that it's closed-minded to assume that natural science is the only science there is.