Gnosticism, derived from a Greek word gnosis meaning 'knowledge', is applied to a philosophical and religious movement that influenced the Mediterranean world from the first century BC to the third century AD. Its name is derived from the fact that it promised salvation through a secret knowledge (gnosis) or understanding of reality possessed by its followers. The term designates a variety of sects, all promising salvation through an occult knowledge that they claimed was revealed to them alone.
Christian ideas were quickly incorporated into these syncretistic systems, and by the 2d cent. A.D. Gnosticism posed a serious threat to Christianity; the early Christians fought vigorously against these dangerous teachings.
Gnosticism taught that the God of creation was so remote from the creature that he ruled the universe by a number of intermediate deities (gods) some good, and some evil. These gods decreased in dignity as they got nearer to mankind. Gnostics also had a graduated scale of mankind: (1) The Higher Knowledge Class (the gnostics themselves, of course). (2) The "can be saved" class (believing their faith plus their works would save them). (3) The hopelessly lost class.
Gnosticism was infinately complex. One common teaching was that matter was evil so Jesus could not have had a literal body (Docetism), or that there were two Christs (1) the historical Jesus who was a mere man and the son of Joseph and Mary (2) and the heavenly non-incarnate Logos who acted through the earthly Jesus. John spoke out against this heresy in the early church, 1John:2:22: "Who is a liar but he that denieth that Jesus is the Christ? He is antichrist, that denieth the Father and the Son."
Most Gnostic systems have three common points. (1) Dualism - an essential antagonism between "good" and "evil." (2) Demiurge - the Creator of the universe who was separate from God. (3) Docetism - The belief that the humanity of Christ was an illusion.
Doctrinally there were three types of Gnosticism. (1) Pagan - Nicolaitanes and Manichaeans (2) Jewish - Cerinthus, Basilides, and Valentinus (3) Christian - Satuminus, Marcion, Tatian.
There were as many divisions of Gnosticism as there were Gnostics, but they were primarily divided geographically into Alexandrian (Basilides and Valentinus) and Syrian (Saturninus and Tatian).
John wrote against this heresy in 1 John (the key word being KNOW, which occurs 30 times in the short book). He taught that we cannot claim to "know" God without keeping the Commandments, or else, we are liars. 1John:2:4: "He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him."
Gnostic thought may be seen as the foundation of many of the forthcoming controversies which plagued the early churches.
Many Gnostic ideas are still present today in the form of Mormonism (with its teaching of attainable godhood) and Roman Catholicism (with its mystical concept of the sacraments and its teaching of a remote God Who can only be approached through intermediaries such as saints, angels, and Mary, and its division of men into higher and lower orders, as well as its emphasis upon asceticism).
Dualism underlies much of Gnostic thought. Good and evil, light and darkness, truth and falsehood, spirit and matter were regarded as being in opposition to one another. The Universe and human experience were depicted by a radical fracture between the spiritual, which was real, and the physical, which was illusory. This disjunction resulted from a "cosmic tragedy", described in several ways by Gnostic mythology, as a consequence of which sparks of deity became ensnared in the physical world. These could be freed only by saving knowledge that was revealed to a spiritual elite by a "supreme messenger" from the spirit world, identified as Seth (one of the sons of Adam), Jesus, or some other figure.
Denial of physical desires and strict austerity, combined with mystical rites of initiation and purification were thought to free the immortal souls of believers from the prison of physical existence. Reunion with divine reality was achieved after a journey of the soul through intricate systems of hostile powers.