Occultism

Have lived this firsthand. Steiner was an occultist, and occultism was very big in the 19th and earlier 20th century. The term occult and 'cult' are related - occult thinking tends to produce cults, a word that has significant negative connotations in our era, because of what some cults have done, but the occult can be discussed separately to that as well.

The specific meaning of occult is 'knowledge of the hidden', of saying there is a deeper spiritual knowledge going beyond the physical sciences and pure reason. Steiner's Theosophy was just one of several occult movements that emerged in the 19th century. They're all marked by claims to access deep, esoteric truths that are separate to common knowledge - that's what occult actually means, as a word. It's why occult thinking produces cults, groups of people unified by their 'special' knowledge. All occultists have some common characteristics, including belief in ancient knowledge (often magic) that has been lost. 

People may at times be surprised what they're getting into bed with in occultist movements, as these parents found out. And many of our other private schools are similar, based on philosophies which would make most peoples' hair curl, that are kept pretty quiet in public debate.

The BBC have also looked at this, at: https://www.bbc.com/news/education-28646118