It is written:
“But there were also false prophets among the people, even as there will be false teachers among you, who will secretly bring in destructive heresies, even denying the Lord who bought them, and bring on themselves swift destruction. 2 And many will follow their destructive ways, because of whom the way of truth will be blasphemed.” (2 Peter 2:1-2)
The early Christians dealt with growing heresies, nearly from the beginning of the church.
The first wave of false teachers came from within the Jewish elements of the church, when Judaizers attempted to bind the Old Testament Law on believers in the Christian Age (cf. Acts 15). The Apostles of Christ clearly demonstrated that Christ’s death on the Cross has brought freedom from the Old Testament Law and the bondage of salvation by lawkeeping in general (cf. Romans 7:1-7; 2 Corinthians 3; Galatians 5;4; Ephesians 2:15; Colossians 2:14; Hebrews 8-9), even while stressing that we live under the New Law of the Spirit (Romans 8:1-4; 1 Corinthians 9:20-21; James 1:25).
Later, a group of heretics arose in the church which were known as the Gnostics. These people attempted to join together the teachings of Christ and the Apostles with pagan Greek religions and philosophies. John the Apostle writes of these heretics throughout 1 John.
There were many different groups of Gnostics, but they often shared the same core beliefs and belief systems. Ken Johnson has well written:
“The father of Gnosticism was Simon Magus, the Simon of Acts 8. Two major schools had developed by 150 AD, the followers of Valentinus and the followers of Basilides. Our knowledge of Gnosticism comes mainly from the early church father Irenaeus, who wrote the five-volume set, Against Heresies and the Gnostic literature itself found at Nag Hammadi, Egypt, in 1945. Irenaeus wrote that Gnostics derived their teachings from the heathen, namely Homer, Plato, Aristotle, the Pythagoreans and others. 16 John the Apostle would not enter a bathhouse where Cerinthus was, and Polycarp said Marcion was the firstborn of Satan. 18 The basic teachings of Gnosticism that the church called heresy are: There are thirty Aeons (gods) that exist in the Pleroma, outside time and space. 1 The goddess, Sophia, created the Demiurge, a creator angel (the god of the Old Testament) who was a tyrant; and being unaware of the Aeons, thought he was the only God. He created man; but Sophia gave man a spirit. 2 Some may be saved if they do enough good works; but some are predestined to go to hell. 4 (works salvation) Gnostics have spirits that are emanations from Sophia. This makes them predestined to be saved. It is IMPOSSIBLE for them to lose their salvation. It does not matter if their behavior is good or evil. The most “perfect” of them addict themselves to evil deeds and are in a habit of defiling the women they convert. 3 Eventually all matter will be destroyed since matter is evil and not capable of salvation. 9, 6 Gnostics will become spirits and will marry the angels. 9 Christ descended upon Jesus at His baptism and left before Jesus went before Pilate. Sophia would not allow Christ to suffer. 9 (Adoptionism) They utter mantras to effect nature. 10 (Hindu mantra and Kabalistic letter magic, Gramera, and emanations) Souls reincarnate. 32 Perfect knowledge is obtained by baptism, spiritual marriage, and last rites. 5 (Sacramentalism) Sophia sent the serpent (the angel Michael or Samael) into the Garden of Eden to free Eve and Adam. By eating from the tree they attained true Gnosis and were set free. 15 Sophia saved Noah from the flood sent by the evil Demiurge. 15 The Demiurge forced Eve into sexual intercourse many times. Eve thereby gave birth to other evil creator angels. 15 (Serpent Seed) At death, some souls enter an intermediate state to be purged of the animal nature before going into the Pleroma. 17 (Purgatory) Later, other Gnostics would add or change some points and found their own Gnostic schools.” (Ken Johnson, Ancient Church Fathers: What The Disciples Of The Apostles Taught, 115-116 (Kindle Edition, emphasis added, M.T.))
It is within the historical narrative of the Gnostics that we begin to see the seeds of what would become the religious system known as Calvinism.