In Christianity, Sabellianism, (also known as modalism, modalistic monarchianism, or modal monarchism) is the nontrinitarian belief that the Heavenly Father, Resurrected Son and Holy Spirit are different modes or aspects of one God, as perceived by the believer, rather than three distinct persons in God Himself.
The term Sabellianism comes from Sabellius, a theologian and priest from the third century.
Meaning and origins
God was said to have three "faces" or "masks" (Greek πρόσωπα prosopa; Latin personae). Modalists note that the only number ascribed to God in the Holy Bible is One and that there is no inherent threeness ascribed to God explicitly in scripture.  The number three is never mentioned in relation to God in scripture, which of course is the number that is central to the word "Trinity". The only possible exceptions to this are the Great Commission Matthew 28:16-20, 2 Corinthians 13:14, and the Comma Johanneum, a disputed text passage in First John (1 John 5:7) known primarily from the King James Version and some versions of the Textus Receptus but not included in modern critical texts. Trinitarians believe that all three members of the Trinity were present as seemingly distinct beings at Jesus' baptism, and believe there is other scriptural evidence for Trinitarianism (see main page for details). Modalism has been mainly associated with Sabellius, who taught a form of it in Rome in the third century. This had come to him via the teachings of Noetus and Praxeas.
Hippolytus of Rome knew Sabellius personally and mentioned him in the Philosophumena. He knew Sabellius disliked Trinitarian theology, yet he called Modal Monarchism the heresy of Noetus, not that of Sabellius. Sabellianism was embraced by Christians in Cyrenaica, to whom Demetrius, Patriarch of Alexandria, wrote letters arguing against this belief.
Christian Modalistic monarchianism has its origin by means of influence in Greek pagan philosophy, including pagan philosophers like Euclid and Aristotle, who based their logic on Monism and Aristotle's arguments around his concept energeia (i.e. energy) called metaphysics. As the concept that ontology (also generally referred to as metaphysics) can be reduced to either a single detectable substance (called substance theory) and or a single being (the concept of the Absolute). Aristotelian logic is the way ontologically or via metaphysics that Hellenic pagan philosopher Aristotle reasoned (Aquinas analytically, Zeno, Plato and Socrates dialectically, Aristotle syllogistically) to deconstructed human consciousness and existence and being. In order to represent their view of the monad or single-ness (unity of all things). As unity or oneness in the "idea" of God and God's ousia as the essence or universal category above finite being.
Full article ▸