Monarchianism, a Christian heresy that developed during the 2nd and 3rd centuries. It opposed the doctrine of an independent, personal subsistence of the Logos, affirmed the sole deity of God the Father, and thus represented the extreme monotheistic view. Though it regarded Christ as Redeemer, it clung to the numerical unity of the Deity. Two types of Monarchianism developed: the Dynamic (or Adoptionist) and the Modalistic (or Sabellian).
Dynamic Monarchianism held that Christ was a mere man, miraculously conceived, but constituted the Son of God simply by the infinitely high degree in which he had been filled with divine wisdom and power. This view was taught at Rome about the end of the 2nd century by Theodotus, who was excommunicated by Pope Victor, and taught somewhat later by Artemon, who was excommunicated by Pope Zephyrinus. About 260 it was again taught by Paul of Samosata. It is the belief of many modern Unitarians.
Modalistic Monarchianism took exception to the “subordinationism” of some of the Church Fathers and maintained that the names Father and Son were only different designations of the same subject, the one God, who “with reference to the relations in which He had previously stood to the world is called the Father, but in reference to His appearance in humanity is called the Son.” It was taught by Praxeas, a priest from Asia Minor, in Rome c. 206 and was opposed by Tertullian in the tract Adversus Praxean (c. 213), an important contribution to the doctrine of the Trinity. See also Sabellianism; Adoptionism.