Christian denominations established in the 2nd century

thumb|right|Apostles in the New Testament|The Apostles receiving the [[Paraclete in Acts. Montanus, the founder of Montanism, claimed to have also received the Paraclete.]]

Marcionism was an early Christian dualistic belief system originating with the teachings of Marcion of Sinope in Rome around 144. Marcion was an early Christian theologian, evangelist, and an important figure in early Christianity. He was the son of a bishop of Sinope in Pontus. About the middle of the 2nd century (140–155) he traveled to Rome, where he joined the Syrian gnostic Cerdo.

The Encratites ("self-controlled") were an ascetic 2nd-century sect of Christians who forbade marriage and counselled abstinence from meat. Eusebius says that Tatian was the author of this heresy. It has been supposed that it was these Gnostic Encratites who were chastised in the epistle of 1 Timothy (4:1–4).

The Ophites, also called Ophians (Greek Ὀφιανοί Ophianoi, from ὄφις ophis "snake"), were a Christian Gnostic sect depicted by Hippolytus of Rome (170–235) in a lost work, the Syntagma ("arrangement").

The Basilidians or Basilideans were a Gnostic sect founded by Basilides of Alexandria in the 2nd century. Basilides claimed to have been taught his doctrines by Glaucus, a disciple of St. Peter, though others stated he was a disciple of the Simonian Menander.

The Archontics, or Archontici, were a Gnostic sect that existed in Palestine, Syria and Armenia, who arose towards the mid 4th century CE. They were thus called from the Greek word , "principalities", or "rulers", by reason that they held the world to have been created and ruled by malevolent Archons.

The Carpocratians (Greek: Καρποκρατιανοὶ) were a Gnostic sect partially based on Platonism that was established in the 2nd century AD and existed until the 6th century. It was named after Carpocrates of Alexandria, its founder, and gained its final form in the writings of his son, Epiphanes. Only fragmentary sources remain about their beliefs and practices, and proto-orthodox Christians of the time mischaracterised their theology to discredit them, accusing them of debauchery.