Thomasines in the context of Syrian

Gnosticism (from Ancient Greek γνωστικός (gnōstikós) 'having knowledge'; Koine Greek: [ɣnostiˈkos]) is a collection of religious and philosophical ideas and systems that coalesced in the late first century AD among sects of early Christianity and other faiths. It is not a singular, homogeneous tradition or religion, but an umbrella term used by modern scholars to describe different groups and beliefs that shared certain characteristics. These diverse Gnostic groups generally emphasized personal spiritual knowledge (gnosis) above the authority, traditions, and proto-orthodox teachings of organized religious institutions. The Gnostic worldview typically distinguished between a hidden, uncorrupted supreme being and a flawed demiurge responsible for creating material reality. Gnostics held this material existence to be evil and believed the principal element of salvation was direct knowledge of the supreme divinity, attained via mystical or esoteric insight. Many Gnostic texts deal not in concepts of sin and repentance, but with illusion and enlightenment.

Although the exact origins of Gnosticism cannot be traced, Gnostic writings flourished among certain Christian groups in the Mediterranean during the second century. In the Gnostic Christian tradition, Christ was seen as a divine being that had taken human form in order to lead humanity back to recognition of its own divine nature. Judean–Israelite Gnosticism, including the Mandaeans and Elkesaites, blended Jewish-Christian ideas with Gnostic beliefs focused on baptism and the cosmic struggle between light and darkness. Syriac–Egyptian groups like Sethianism and Valentinianism combined Platonic philosophy and Christian themes, seeing the material world as flawed but not wholly evil. Other traditions include the Basilideans, Marcionites, and Thomasines. Manichaeism, which adopted Gnostic concepts such as cosmic dualism, emerged as a major religious movement in the third century, briefly rivaling Christianity.

The Gospel of Thomas (also known as the Coptic Gospel of Thomas) is a non-canonical sayings gospel. It was discovered near Nag Hammadi, Egypt, in 1945 among a group of books known as the Nag Hammadi library. Scholars speculate the works were buried in response to a letter from Bishop Athanasius declaring a strict canon of Christian scripture. Most scholars place the composition during the second century, while some have proposed dates as late as 250 AD and others have traced its signs of origins back to 60 AD. Some scholars have seen it as evidence of the existence of a "Q source" that might have been similar in its form as a collection of sayings of Jesus, without any accounts of his deeds or his life and death, referred to as a sayings gospel, though most conclude that Thomas depends on or harmonizes the Synoptics.

The Coptic-language text, the second of seven contained in what scholars have designated as Nag Hammadi Codex II, comprises 114 sayings attributed to Jesus. Almost two-thirds of these sayings resemble those found in the canonical gospels and its editio princeps counts more than 80% of parallels. Experts speculate that the gospel's other sayings were added from Gnostic tradition. Its place of origin may have been Syria, where Thomasine traditions were strong. Other scholars have suggested an Alexandrian origin.

Pseudo-Gnosticism is a term used for groups which have been labelled Gnostic, either by their contemporaries or modern historians even when the accuracy of this label is questionable. Examples include some ancient groups like the Thomasines or the Bardaisanites, but more often refer to medieval sects accused of Gnosticism by other Christian authorities such as the Paulicians or according to some, the mainstream Cathars.

Similar accusations occurred during the Christianisation of Ireland and the Baltic Crusade, when the Roman Catholic Church would accuse these of worshipping gods from Roman Paganism.