"D.M. Panton has well outlined the main features of full-grown Gnosticism as follows.
1. Historically, it absorbed non-Christian thought into the Christian faith.
2. Philosophically, it lodged sin in matter and, therefore, repudiated the Creator as either impotent or evil.
3. Practically, numerous Gnostic schools prohibited marriage as multiplying incurable matter.
4. Similarly, numerous Gnostics prohibited the eating of certain foods, such as wine and meat, as being inherently evil.
5. Theologically, the [Adonai] of the Old Testament was portrayed as the tribal God of Israel. He was denounced as an alien and hostile deity.
6. Christologically, it separated Jesus from the Christ, denying both the deity and humanity of the Lord.
7. Inevitably, it sank finally into irreparable apostasy. Apostasy is not merely corruption of the truth; it is a total change of the truth or a complete abandonment of the faith previously held," (D.M. Panton, Present Day Pamphlets: 'Gnosticism: The Coming Apostasy", as quoted in Exploring Colossians and Philemon by John Phillips)
NOTE: To summarize, Christian Gnosticism (1) was syncretic; (2) viewed matter as sinful; (3) prohibited marriage; (4) prohibited certain foods and drinks; (5) denied the Divinity (and humanity) of Yeshua; (6) led to apostasy.
"The name 'gnosticism' derives from the Greek word gnosis, which mean 'knowledge.' According to the Gnostics, they possessed a special, mystical knowledge, reserved for those with true understanding. That knowledge was the secret key to salvation.
Salvation was the main concern for the Gnostics. Drawing from several sources, they came to the conclusion that all matter is evil, or at best unreal. A human being is in reality an eternal spirit...imprisoned in a body...Therefore, the Gnostic's final goal is to escape from the body and this material world....Gnosticism affirmed that originally all reality was spiritual. The supreme being had no intention of creating a material world, but only a spiritual one....But, since this world was made by a spiritual being, there are still 'sparks'...of spirit in it. it is these that have been imprisoned in human bodies and must be liberated through gnosis.
In order to achieve that liberation, a spiritual messenger must come to this world, to waken us from our 'dream.' Our spirits are 'asleep' within our bodies, being driven by the impulses and passions of the body, and someone must come from beyond to remind us who we really are and to call us to struggle against our incarceration. This messenger brings the gnosis, the secret knowledge...necessary for salvation....In order to reach the spiritual 'fulness,' we must break through each of those spheres. The only way to do this is to have the secret knowledge that opens the way--much like a spiritual password...
In Christian gnosticism--one should always remember that there were also non-Christian Gnostics--that messenger is Christ...." pgs 59, 60 of The Story of Christianity by Justo L. Gonzalez