This is mainly addressed to the people of knowledge, like a scholar or Mufti. I was reading a post about perennialism and I was wondering if it was allowed in Islam or not.. I thought that Martin Lings, Hamza Yusuf and Schon are all Muslims... but now I have doubts. So what is the real story. (Please note, if you are biased or have no knowledge about this topic, please refrain from "commenting") What exactly do they believe in that is contrary to the teachings of Allah and his messenger? Please help me/us understand.