1. Gnostic Movements (1st–2nd Century)

These are the earliest genuine heresies. They introduced ideas completely foreign to the Hebrew worldview:

• Secret knowledge (gnosis)
• A non‑historical, non‑Jewish “Christ”
• Dualistic cosmology (spirit = good, matter = evil)
• Rejection of the Hebrew Scriptures

Major branches:

• Sethian Gnostics
• Valentinian Gnostics
• Basilideans
• Thomasine Gnostics (Syrian mystical schools)

These are the first true departures from the apostolic faith.

2. The Marcionites (2nd Century)

Marcion rejected:

• The God of the Old Testament
• The Hebrew Scriptures
• The Jewish roots of the Gospel

He created his own canon (edited Luke + 10 Pauline letters).

This is a radical break from the apostolic message.

3. Sabellianism (2nd–3rd Century)

Sabellius was teacher active in Rome. He taught Modalistic Monarchianism, which claimed God is one Person who appears in three different modes, this denied the distinction between Father, Son, and Holy Spirit.

His teaching:

• One God who appears in different “modes”
• In the Old Testament He was YHVH
• In the Gospels He was the Messiah
• Now He is the Holy Spirit

In this system, there is only one being who changes identity and rolls over time.

This directly contradicts the apostolic witness of the Father, Son and Holy Spirit interacting with one another and with us.

4. The Montanists (2nd Century)

They taught two eternal gods (light vs. darkness). This is not Biblical in any sense.

• A prophetic movement in Asia Minor
• Emphasized spiritual gifts and strict holiness
• Condemned for challenging episcopal authority

5. Manichaeans (3rd Century)

A full-blown alternative religion blending:

• Zoroastrian dualism
• Gnostic cosmology
• Buddhist elements
• Christian terminology

6. The Monarchians / Modalists (2nd–3rd Century)

• Taught the oneness of God without eternal distinctions
• Included Sabellius
• Rejected by Trinitarian bishops

7. The Novatianists (3rd Century)

• A rigorist movement
• Opposed the readmission of lapsed believers
• Formed their own bishops and communities

8. The Donatists (4th–5th Century)

• North African movement
• Rejected bishops who cooperated with Rome
• Strong in Carthage for centuries
• Opposed by Augustine

9. The Pneumatomachians (4th Century)

They believed the Spirit was:

• A created being
• A ministering power
• A servant of the Father and the Son
• Not eternal

10. Pelagians (4th–5th Century)

Pelagius taught:

• Humans are born morally neutral
• Grace is not necessary for salvation
• The will alone can achieve righteousness

This contradicts the apostolic teaching on sin and grace.

11. The Nestorian / Dyophysite Movement (5th Century)

• Followers of Nestorius
• Rejected the title “Theotokos”
• Condemned at Ephesus (431)
• Became the Church of the East (your first branch)

12. The Miaphysite Movement (5th Century)

• Rejected Chalcedon (451)
• Became the Oriental Orthodox Churches (your second branch)