Gnosticism is religious existentialism and the gnostic is in search of the answer to the mystery of existence his quest is for a fragment of the divine its a quest for redeeming knowledge and a quest for oneself its far more than just a doctrine in this sense its the historical dimension of the traditions cultural figures
Gnosticism is the belief that one knows everything, a belief that is inherently flawed, except by God Himself. Agnosticism, a much more appropriate belief for us, is a belief that one doesn't know everything.
Gnosticism can be read about in many books. The Gnostic Society has their own Library in which everything about the Gnosticism can be learned or studied.
there is no scientific basis for Gnosticism or orthodox (mainstream) Christianity.
Simon Magus
Pneuma
No book in the bible addresses Gnosticism, you are looking for Against Heresies as written by a father of the church, Irenaeus.
The opponents of Gnosticism were primarily early Christian leaders and theologians, such as Irenaeus and Tertullian. They argued against Gnosticism's belief in secret knowledge and its rejection of the material world, emphasizing instead the importance of orthodox Christian doctrine and the belief in a loving creator God.
Test
Deirdre Joy Good has written: 'Reconstructing the tradition of Sophia in Gnostic literature' -- subject(s): Gnosticism, Wisdom (Gnosticism) 'Mariam, The Magdalen, And The Mother'
Ithamar Gruenwald has written: 'Messiah & Christos' 'From apocalypticism to Gnosticism' -- subject(s): Apocalyptic literature, Gnosticism, History and criticism, Judaism, Merkava in rabbinical literature, Mysticism
Mary Ann Donovan has written: 'Irenaeus' teaching on the unity of God, and his immediacy to the material world, in relation to Valentinian Gnosticism' -- subject(s): Gnosticism, Valentinians
Daniel L. Hoffman has written: 'The status of women and Gnosticism in Irenaeus and Tertullian' -- subject(s): Women in Christianity, Gnosticism, Social conditions, History, Women
The common belief is that Gnosticism originated as a branch of Christianity. There are some theories that claim the central ideas of Gnosticism existed before the birth of Christ. These ideas, of a dualistic religion (two Gods), still prevail today in modern Christianity with the teachings of one supremely good God of Heaven and one sinful, loathsome God of Hell.