Any study of Church history can run aground when dealing with the various heresies of the Second through Fourth Centuries. The list of heretical ideas is a long and bewildering one. For those who are attempting to study Church history during those centuries, here is a brief list with definitions for the major heresies of the times. Please note the definition of each heresy is only a very general one. Many of the groups had subdivisions, such as the Arians.
Adoptionists—Jesus became the Messiah at a certain point in time. Typical adoptionist theories taught Jesus became the Messiah at His Birth or His Baptism.
Agapetae—Celibate men and women living together. Condemned by St. Jerome.
Apollinarians—The Word was directly united to a fleshly body without a soul.
Arians—Subordinationists who declared the Son to be a creation of the Father. Therefore, there is no Holy Trinity in Arian theology. This group was named after the priest Arius and almost coopted Christianity. The extent of Arian power was demonstrated by the famous St. Jerome quote, “The whole world groaned and marveled to find itself Arian.” The First Ecumenical Council was called by Constantine the Great to deal with the Arian heresy, resulting in the Nicene Creed. Alexander of Alexandria and Athanasius of Alexandria were the major proponents of orthodox Christianity. There were several groups of Arians. This is not an all-inclusive list:
- Anonmoeism—Most radical of the Arians. They held the Son was different in all ways from the Father.
- Eudoxians—The Son was similar to the Father, but this was a moral similarity.
- Homoens—Arians who rejected not only the doctrine of one essence (homoousious or consubstantial) but rejected even the similarity of essence. This is the form of religion most of the Germanic peoples adopted.
- Homoiousians—Believed the members of the Trinity were of similar, but not one essence. It was thought to be a compromise between the orthodox and the Arians. St. Basil the Great was originally a Homoiousian. Eventually, the argument that similarity implied difference triumphed and Homoiousianism was defeated. Have you ever wondered where the phrase “there is not an iota of difference” came from? Orthodox Christians were homoousians, and still are. They believe the members of the Trinity were of one Notice the Greek letter iota was inserted into the word homoiousian to change its meaning.
- Pneumatomachoi—Arians who rejected the Divinity of the Holy Spirit. Also sometimes called imprecisely Semi-Arians or Macedonians. Condemned at the Second Ecumenical Council of Constantinople in 381. Basil the Great and Athanasius the Great were opponents of the Pneumatomachoi. Basil’s great book “De Spiritu Sancto” was written to explain the divinity of the Holy Trinity.
Eunomians—Since God was a simple being, He was perfectly comprehensible. St. Gregory Palamas was an opponent.
Heterodox—Schismatic, as opposed to the Orthodox.
Marcionites—Followers of Marcion, who was almost elected Pope of Rome. They believed the “God of the Old Testament” was an evil God. The Demiurge, who created the world, was an agent of this evil god. They rejected the Old Testament as well as much of the New Testament, keeping only the letters of St. Paul and parts of the Gospel of Luke as canonical.
Meletians/Donatists—Those who lapsed in the face of persecution should not be readmitted into the Church. Donatists were located predominantly in the civil diocese of Africa, while the Meletians were predominant in the civil diocese of Egypt.
Novationists—The so-called “Pure Ones” who refused to reconcile those who apostated during persecutions. They were hostile to the Arians, since they were orthodox in their beliefs.
Paulianists—There was only one divine person, the Father. Jesus was a mere man gifted with a high degree of grace.
Sabellianism—Sabellius of Rome taught modalism, the belief there was no real distinction between the Persons of the Trinity. They were simply three modes of the same Divinity.
- Marcellians: Sabellians who believed God was a unique person Whose pre-existing Word had no distinct existence.
- Photinians—Modalists that were also Adoptionists.
 Athanasius of Alexandria also commonly referred to as Alexander the Great was a deacon for Alexander of Alexandria. Athanasius succeeded Alexander as bishop of Alexandria shortly after the end of the First Ecumenical Council
 The term diocese originally meant a subdivision of the Roman Empire. Various provinces of the Empire were grouped into dioceses. The Roman Catholic Church used the same terminology but with different meanings. Catholic dioceses are grouped into ecclesiastical provinces.