Gnosticism
Gnosticism (from the Greek word "gnosis" meaning "knowledge") was a big tent term referring to many different heresies, especially in the first few centuries of Christianity.
Traditionally most Gnostic adherents reject all canonical scripture and are opposed to monotheism, salvation by faith alone, and Jesus as the fulfilment of Judaism, but instead the destroyer of it.
Although the founding of Gnosticism is traditionally attributed to Simon Magnus, but it more likely originates amongst the followers of the heretical antisemite, Marcion. His followers, known as marcionites, rejected the Old Testament and God the Father as evil and distinct from the righteous New Testament and God the Son. Marcion's canon only included one Gospel (an edited version of the Gospel of Luke) and some of the Epistles of Paul.
This doctrine went on to influence the doctrine of the theologian, Valentinus, who attempted to become the Bishop of Rome. He believed in a pantheon of gods leading to God the Father, who he named Yaldabaoth, who was the evil creator of the world. Because the world was created by an evil god, Valentinus taught that the aim of Jesus was to help us to escape nature and return to heaven, which he called the pleroma.
The Gnostics wrote many false texts but their religion was based on the acquisition of secret knowledge. Their beliefs and methods are most comparable to the modern heresies of the "prosperity gospel" or "rapture theology".
The beliefs of Mandaeism, Manicheaism, Catharism, Islam, Mormonism, Freemasonry and New Age spirituality all are influenced by the Gnostics.