Those who are usually meant by the name were a section of the Monophysites, who had great influence in the second half of the sixth century, but have left no traces save a few scanty notices in John of Ephesus, Photius, Leontius, etc. Their founder is said to have been a certain John Ascunages, head of a Sophist school at Antioch. But the principal writer was John Philoponus, the great Aristotelean commentator. The leaders were two bishops, Conon of Tarsus and Eugenius of Seleucia in Isauria, who were deposed by their comprovincials and took refuge at Constantinople. There they found a powerful convert and protector in Athanasius the Monk, a grandson of the Empress Theodora. Philoponus dedicated to him a book on the Trinity. The old philosopher pleaded his infirmities when he was summoned by Justinian to the Court to give an account of his teaching. But Conon and Eugenius had to dispute in the reign of Justin II (565-78) in the presence of the Catholic patriarch, John Scholasticus (565-77), with two champions of the moderate Monophysite party, Stephen and Paul, the latter afterwards Patriarch of Antioch. The Tritheist bishops refused to anathematize Philoponus, and brought proofs that he agreed with Severus and Theodosius. They were banished to Palestine, and Philoponus wrote a book against John Scholasticus, who had given his verdict in favor of his adversaries. But he developed a theory of his own as to the Resurrection (see Eutychianism) on account of which Conon and Eugenius wrote a treatise against him in collaboration with Themistius, the founder of the Agnoetai, in which they declared his views to be altogether unchristian. The two bishops together with a deprived bishop named Theonas proceeded to consecrate bishops for their sect, which they established in Corinth and Athens, in Rome and Africa, and in the Western Patriarchate, while their agents travelled through Syria and Cilicia, Isauria and Cappadocia, converting whole districts, and ordaining priests and deacons in cities, villages, and monasteries. Eugenius died in Pamphylia; Conon returned to Constantinople. We are assured by Leontius that it was the Aristoteleanism of Philoponus which made him teach that there are in the Holy Trinity three partial substances (merikai ousiai, idikai theotetes, idikai phuseis) and one common. The genesis of the heresy has been explained (for the first time) under Monophysites and Monophysitism. where an account of Philoponus’s writings and those of Stephen Gobarus, another member of the sect, will be found.
In the Middle Ages Roscellin of Compiegne, the founder of Nominalism, argued, just like Philoponus, that unless the Three Persons are tres res, then the whole Trinity must have been incarnate. He was refuted by St. Anselm.
Among Catholic writers, Pierre Faydit, who was expelled from the Oratory at Paris in 1671 for disobedience and died in 1709, fell into the error of Tritheism in his “Eclaircissements sur la doctrine et l’histoire ecclesiastiques des deux premiers siecles” (Paris, 1696), in which he tried to make out that the earliest Fathers were Tritheists. He was replied to by the Premonstratensian Abbot Louis-Charles Hugo (“Apologie du systeme des Saints Peres sur la Trinity,” Luxemburg, 1699). A canon of Treves named Oembs, who was infected with the doctrines of the “Enlightenment”, similarly attributed to the Fathers his own view of three similar natures in the Trinity, calling the numerical unity of God an invention of the Scholastics. His book, “Opuscula de Deo Uno et Trino” (Mainz, 1789), was condemned by Pius VII in a Brief of July 14, 1804. Gunther is also accused of Tritheism.
Among Protestants, Heinrich Nicolai (d. 1660), a professor at Dantzig and at Elbing (not to be confounded with the founder of the Familisten), is cited. The best known is William Sherlock, Dean of St. Paul’s, whose “Vindication of the Doctrine of the Trinity” (London, 1690) against the Socinians was attacked by Robert South in “Animadversions on Dr. Sherlock’s Vindication” (1693). Sherlock’s work is said to have made William Manning a Socinian and Thomas Emlyn an Arian, and the dispute was ridiculed in a skit entitled “The Battle Royal”, attributed to William Pittis (1694?), which was translated into Latin at Cambridge. Joseph Bingham, author of the “Antiquities”, preached at Oxford in 1695 a sermon which was considered to represent the Fathers as Tritheists, and it was condemned by the Hebdomadal Council as falsa, impia et hoeretica, the scholar being driven from Oxford.