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Frend, W. H. C. The Rise of Christianity. Philadelphia: Fortress Press, 1984.
Grant, R. M. Gnosticism and Christianity. New York: Harper and Row, 1966.
Green, Henry A. The Economic and Social Origins of Gnosticism. Atlanta: Scholars Press, 1985.
Jonas, H. The Gnostic Religion: The Message of the Alien God and the Beginnings of Christianity. Boston: Bacon Press, 1963.
Pagels, E. Gnostic Gospels. London: Weidenfeld and Nicolson, 1979.
Riemer, R. Gnosis and Faith in Early Christianity. London: SCM Press, 1999
Rudolph, K. Gnosis: The Nature and History of an Ancient Religion. Translated by Robert M. Wilson. Edinburgh: T & T Clark, 1983.
The work which was originally a dissertation produced in 1985 by Henry A. Green entitled The Economic and Social Origins of Gnosticism is quite helpful and approaches the socio-religious phenomenon of Gnosticism from a socio-economic point of view. Green is quite methodological and thorough in his book, offering insights that will probably not be found elsewhere. His study, as he writes, "should be regarded as a pilot study, an attempt to apply social-scientific paradigms to the examination of ancient religions, and specifically Gnosticism" (p. 18).
You may also remember me saying that ancient Gnostics usually were libertines or ascetics. Some went for the gusto while others abstained from certain foods, drink and they lived celibate lives. For these thinkers, the world of matter was thought to be evil, alienated from God, and produced by intermediate aeons.