Sufism/Islam
There was a whole series of posts on Islamophobia and related issues at Darwiniana.
We should be careful here that our topic is The Gurdjieff Con, but one of the significant issues for students of sufism is the hidden hostility to those who are not a part of Islam. Most real sufis would not countenance such a bias, but in fact it is omnipresent, a very strong component in the near universal failure of students of sufism (or the seemingly unrelated Gurdjieffianity!) to get anywhere.