Question: "What is modalism / Modalistic Monarchianism?"
Answer: Modalism and Monarchianism are two false views of the nature of God and of Jesus Christ that appeared in the second and third centuries AD. A modalist views God as one Person instead of three Persons and believes that the Father, Son, and Spirit are simply different modes or forms of the same divine Person. According to modalism, God can switch among three different manifestations. A Monarchian believes in the unity of God (the Latin word monarchia meant “single rule”) to the point that he denies God’s triune nature. Both modalism and Monarchianism inevitably hold to the doctrine of Patripassianism, the teaching that God the Father suffered on the cross with (or as) the Son, and are closely related to Sabellianism.
Monarchianism took two primary forms, Dynamic (or Adoptionist) Monarchianism and Modalistic Monarchianism. Dynamic Monarchianism started with an errant view of the nature of Jesus, specifically, that He was not God but was, at His baptism, empowered by God to do the wonders He did. Modalistic Monarchianism, on the other hand, took the modalistic view that Jesus was God, but only by virtue of the fact that Jesus was one of God’s “manifestations.” According to Monarchianism, the Logos of God has no separate, personal existence of its own. The biblical terms Father, Son, and Spirit are only different names for the same Person, according to the Monarchian.
Modalistic Monarchianism teaches that the unity of God is incompatible with a distinction of Persons within the Godhead. According to modalism, God has variously manifested Himself as the Father (primarily in the Old Testament), as the Son (primarily from Jesus’ conception to His ascension), and as the Holy Spirit (primarily after Jesus’ ascension into heaven). Modalistic Monarchianism has its roots in the false teaching of Noetus of Smyrna around AD 190. Noetus called himself Moses and called his brother Aaron, and he taught that, if Jesus was God, then He must be the same as the Father. Hippolytus of Rome opposed this falsehood in his “Contra Noetum.” An early form of Modalistic Monarchianism was also taught by a priest from Asia Minor named Praxeas, who traveled to Rome and Carthage about AD 206. Tertullian countered the teaching of Praxeas in “Adversus Praxean” around 213. Modalistic Monarchianism and its related heresies were also refuted by Origen, Dionysius of Alexandria, and the Council of Nicea in 325.
A form of Monarchianism still exists today in Oneness Pentecostalism. In oneness theology, which is anti-Trinitarian, there are no distinctions among the Persons of the Godhead. Jesus is God, but He is also the Father and the Spirit. In a slight deviation from ancient modalism, Oneness Pentecostals teach that God is able to manifest Himself in all three “modes” simultaneously, such as at Jesus’ baptism in Luke 3:22.
The Bible presents God as one God (Deuteronomy 6:4), but then speaks of three Persons—the Father, the Son, and the Holy Spirit (Matthew 28:19). How these two truths harmonize is inconceivable to the human mind. When we attempt to understand the inscrutable, we will always fail to varying degrees. But Scripture is plain: God exists in three co-eternal, co-equal Persons. Jesus prayed to His Father (Luke 22:42) and now sits on the right hand of the Father in heaven (Hebrews 1:3). The Father and the Son sent the Spirit into the world (John 14:26; 15:26). Modalism and the more specific Modalistic Monarchianism are theologically dangerous because they attack the very nature of God. Any teaching that does not acknowledge God as three distinct Persons is unbiblical.