Muslims and mainstream scholars of Islam define Sufism as simply the name for the inner or esoteric dimension of Islam[18] which is supported and complemented by outward or exoteric practices of Islam, such as Islamic law.[19] In this view, "it is absolutely necessary to be a Muslim" to be a true Sufi, because Sufism's "methods are inoperative without" Muslim "affiliation".[20] Orthodox views also maintain that Sufism is unique to Islam.[15][21] In contrast, author Idries Shah states Sufi philosophy is universal in nature, its roots predating the rise of Islam and Christianity.[22] Some neo-Sufis in Western countries allow non-Muslims to receive "instructions on following the Sufi path".[23] Some Muslim opponents of Sufism also consider it outside the sphere of Islam.[18][24]
