Monarchianism, in Christianity, a Christological position that opposed the doctrine of an independent, personal subsistence of the Logos and affirmed the sole deity of God the Father. Thus, it represented the extreme monotheistic view.
Though it regarded Jesus 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). Monarchianism emerged during the 2nd century and circulated into the 3rd century; it was generally regarded as a heresy by the mainstream of Christian theology after the 4th century.
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.
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 about 206 and was opposed by Tertullian in the tract Adversus Praxean (c. 213), an important contribution to the doctrine of the Trinity.