The Early Church to the Council of Constantinople (Heresy History 1: up to 381)

Very early in the Christian Church there was much discussion about exactly who Jesus was and what his nature was, along with the nature of the trinity.

• Psilanthropism is the view that Jesus was only a man and not God's Son, which was taught originally by the Jews who did not accept Him. After Jesus Christ's ministry, his followers became known as "followers of the way" and later Christians. Judaism and Christianity eventually split into two separate religions.
• Rabbinic Judaism of today rejects Jesus as the Messiah and has its roots in the the Pharisees of Biblical times.
• Ebionism was a movement of Jews who regarded Jesus as the Messiah, but rejected his divinity.

• Gnosticism was a Greek philosophy that had widely varying teaching and practices, but generally were very strong dualists, who taught that the world and all material substance is so corrupt and bad that they should be shunned. They taught material substance was so bad that a true god could not have created it, so they believed in a demiurge creator. Therefore, they were strong ascetics who believed that a soul needed to be separated from its body before it could be perfect.This Gnostic philosophy affected certain early Christians.
• Valentinianism, Sethianism, Ophitism, Nassenism, Sethianism,  Mandaeism (or Mandaeanism), and Manichaeism, along with its sub-sect Priscillianism were some of the many early sects of Gnostics that taught some very strange stuff. 
• Encratitism, meaning, "self-controlled" was one of the earliest known sects claiming to be Christian. They forbade marrying, drinking alcohol, and eating meat and they rejected St. Paul and his teachings. They are probably who is mentioned in 1 Timothy 4:3. They are also mentioned and condemned by Irenaeus, Clement, and Origen.
• Severianism was a later sect of Encratites that had a small revival under a man named Severus.
• Docetism, which means "to seem", was another Gnostic heresy that was common in early Christianity. The word Docetism has connotations of an apparition or phantom. They taught that Christ only appears to be human and that his human form was an illusion, because flesh is sinful.

• Marcionism taught that Christ was so divine he could not have been human and that God lacked a material body, so Jesus only appeared as flesh and blood and his body was a phantasm.
• Non-Marcionist Docetism taught that Jesus was a man in the flesh, but that Christ is a separate entity who entered Jesus body in the form of a dove at his baptism. That entity, then left his body upon his death on the cross.

• Monarchianism, which is the idea that God is a single person, not a trinity, and was another early large class of heresies.
• Unitarianism teaches that there is one god, who is one person, and Jesus is not him, but the son of God in some other sense.
• Modalism or Sabellianism teaches that God is one person appearing in different modes.
• Patripassianism focused on the teaching that God the Father was incarnate and suffered on the cross.
• Subordinationism taught that the Son and Spirit are subordinate to the father. They claimed the Father was the only one to have full divine nature, trying to be a middle ground between unitarianism and modalism.
• Partialism teaches that God is one person with three different parts that have different functions.
• Dynamic Monarchianism teaches that Jesus is not co-eternal, but granted godhood.
• Adoptionism: Jesus was adopted as God's son at either his baptism, resurrection, or ascension.
• Audianism taught that God (the Father) has a human form (Anthropomorphism)
• Montanism popped up sometime in the second century taught that further revelation was a key component to Christianity and they continued to prophecy, whereas the orthodox Christian Church was strictly bound to the limits of scripture.
• Donatism was a schismatic sect, not in communion with the catholic church and were located in Africa.  They were concerned with church discipline and spiritual authority of clergy.
• Circumcellianism was a militant sect of Donatism that prized martyrdom and and denounced property, slavery, and debt.
• Arianism was founded by Arias (AD 250-336), and taught that Jesus Christ was created by the Father before all worlds (not co-eternal with the Father) and was a kind of demiurge through whom everything else was made.

In AD 313 Constantine and Licinius legalized Christianity through the Edict of Milan. In AD 325, Constantine convened the Council of Nicaea (also known as the first ecumenical council) to address the heresies and to develop a common doctrine and statement of faith for Christianity. During this time, Arianism was condemned and the first version of the Nicene Creed was written, that stated that the Son is the same substance (homoousios) as the Father. Shortly after the Council of Nicaea, in AD 330, the Roman Empire split and the Eastern Roman Empire/Byzantine Empire began.

• Arianism declined some places and became more extreme in others after the Council of Nicaea.
• Anomoeanism was an extreme version of Arianism that taught Jesus was not the same substance (heteroousios) as the Father. Basil the Great and Gregory of Nazianzus wrote extensively against anomoeanism.
• Semi-Arianism attempted to bride the gap between trinitarianism and Arianism, by teaching that Jesus was neither created nor uncreated in the sense of other beings and was a "like" substance (homoiousios) with the Father, but not the "same" substance .
• Macedonianism was one group of Semi-Arians who also denied the divinity of the Holy Spirit altogether.
• Euchitism or Messalianism was first mentioned in the 370s and mystical materialism. They taught that the essence of the trinity could be perceived by the senses and takes different forms to do so. They also taught one could come to a state of perfection through prayer, and they denounced the sacraments.

In AD 381, the First Council of Constantinople, or second ecumenical council, was called to refute the Macedonians and Arians. They also confirmed first council of Nicaea and modified the Nicene Creed to include the Holy Spirit.