His belief in a mystical interpretation of Islam gave rise in 1934 to what Khulusi considers his Magnum opus, al-Shakhsiyya al-Muhammadiyya aw Hall al-Lughz al-Muqaddas (The Personality of Muhammad or the Solution of the Sacred Enigma). In it he asserted that the Prophet Muhammad was at one with the universe and God, and that his word was that of God. This was Rusafi's interpretation of the principle of 'revelation' and gave an alternative view to the concept of the 'messenger of God'.