"Gnosticism is a concept of spiritual experience which has its roots in many religious practices and is not restricted to Christianity.
It is also found in the Kabbalah of Judaism, the philosophy of NeoPlatonism, and in modern Iraq a small sect of peasants called Mandaeans (their word for 'knowers') still survives today.
It is a belief system which considers the 'spiritual' world to be the real world and this material world but a product of the negative use of that spirituality.
This is an obvious oversimplification and I ask your kind indulgence.
Approach it openly and perhaps you will find your viewpoints amazingly expanded"
The word "gnosis" is derived from the Greek language, and means "knowledge of an intuitive nature; the intuitive comprehension of spiritual truths."
Gnosis is considered a knowledge that cannot be gained via books or lectures, but rather via one's own direct experiences of reality. Gnosis is often referred to as 'knowledge of the heart', in contrast to knowledge that is obtained through the use of the intellect. Gnosticism is a set of diverse, syncretistic religious movements in Late Antiquity consisting of various belief systems generally united in the teaching that the material cosmos was created by an imperfect god, Yaldabaoth sometimes referred to as the demiurge, with some of the pneuma of the supreme God, which is referred to by several terms including Pleroma and Godhead. The demiurge is identified with Yahweh the God of the Judea-Christian faiths.
The gnōsis referred to in the term is a form of mystic, revealed, esoteric knowledge through which the spiritual elements of humanity are reminded of their true origins within the superior Godhead, being thus permitted to escape materiality. Consequently, within the sects of gnosticism only the pneumatics or psychics obtain gnōsis; the hylic or Somatics, though human, being incapable of perceiving the higher reality, are unlikely to attain the gnōsis deemed by gnostic movements as necessary for salvation. Jesus of Nazareth is identified by some Gnostic sects as an embodiment of the supreme being who became incarnate to bring gnōsis to the earth. In others (e.g. the Notzrim and Mandaeans) he is considered a mšiha kdaba or "false messiah" who perverted the teachings entrusted to him by John the Baptist. Still other traditions identify Mani and Seth, third son of Adam and Eve, as salvific figures.
Whereas Gnosticism has been considered by scholars to originate as a branch of Christianity, alternate theories have proposed traces of Gnostic systems existed some centuries before the Christian Era, thus predating the birth of Jesus. The movement spread in areas controlled by the Roman Empire and Arian Goths, and the Persian Empire; it continued to develop in the Mediterranean and Middle East before and during the 2nd and 3rd centuries. Conversion to Islam and the Albigensian Crusade (1209–1229) greatly reduced the remaining number of Gnostics throughout the Middle Ages, though a few Mandaean communities still exist. Gnostic ideas became influential in the philosophies of various esoteric mystical movements of the late 19th and 20th centuries in Europe and North America, including some that explicitly identify themselves as revivals or even continuations of earlier gnostic groups.The Gnostic teachings contain systems and exercises through which every aspect of the teachings can be personally verified by each individual. Gnosis is not just theoretical, but one hundred percent practical. Through direct experience we surpass the boundaries of belief and disbelief, since both lead to ignorance. Rather than believing or disbelieving, accepting or rejecting, the Gnostic personally verifies in a direct manner the validity of the concepts he or she is studying. This personal verification leads to true knowledge and comprehension, not merely an intellectual or theoretical understanding of the teachings. Through Gnosis one personally learns to experience reality directly, quell the battle between doubt and belief, and comes to know the inner TRUTH."