The religion of the Sufi is not separate from the religions of the world. People have fought in vain about the names and lives of their saviors, and have named their religions after the name of their savior, instead of uniting with each other in the truth that is taught. This truth can be traced in all religions, whether one community calls another pagan or infidel or heathen. Such persons claim that theirs is the only scripture, and their place of worship the only abode of God. Sufism is a name applied to a certain philosophy by those who do not accept the philosophy; hence it cannot really be described as a religion; it contains a religion but is not itself a religion. Sufism is a religion if one wishes to learn religion from it. But it is beyond religion, for it is the light, the sustenance of every soul, raising the mortal being to immortality.
–Inayat Khan, in The Spiritual Message of Hazrat Inayat Khan, Vol. I, The Way of Illumination, Section I – The Way of Illumination, Part III : The Sufi; courtesy of Wikiquote