Monopsychism is the belief that all humans share one and the same eternal consciousness, soul, mind or intellect. It is a recurring theme in many mystical traditions. Monopsychism is a doctrine of Sabianism, Jewish Kabbalah, and Averroism, and is also a part of Rastafarian beliefs. A similar belief in some mystical Judeo-Christian-Islamic traditio...
belief that individuals have a single eternal soul
• (n.) The doctrine that there is but one immortal soul or intellect with which all men are endowed.
Mon`o·psy'chism noun [ Mono- + Greek ... soul.] The doctrine that there is but one immortal soul or intellect with which all men are endowed. 
monopsychism The theory that all souls (or the souls of all mankind) are one; the unity of souls asserted by this theory.