The Alogi (ἄλογοι, also called "Alogians") were a group of Christian heretics in Asia Minor that flourished around 170 CE. What we know of them is derived from their doctrinal opponents, whose literature is still extant, particularly St. Epiphanius of Salamis. It was Epiphanius who coined the name "Alogi" as a wordplay suggesting that they were both illogical (anti-logikos) and they were against the Christian doctrine of the Logos. “
“St. Epiphanius (Haer. LI) gives a long account of the party of heretics who arose after the Cataphrygians, Quartodecimans, and others, and who received neither the Gospel of St. John nor his Apocalypse.”; they instead attributed the two New Testament books to the Gnostic Cerinthus, who was actually an enemy of the Apostle.
Regarding their beliefs, Epiphanius asserts that the Alogians denied the continuation of spiritual gifts in the church in opposition to the Montanists. They explicitly deny the Logos doctrine in John chapter 1 and they deny Johannine authorship by comparing his Gospel with the synoptic Gospels. Their comparative method was considered very foolish in Epiphanius’ opinion who derided them as "stupid". Epiphanius argues that Cerinthus could not have written the Gospel of John because whereas Cerinthus denied the deity of Christ, the Gospel taught Christ's Godhead. Epiphanius contemplates that they may not reject Christ's deity outright, but instead just the “Logos form from which the doctrine is presented in the Gospel.”  He therefore is not so much concerned with their Christology as much as he is concerned with their biblical criticism. Nevertheless, Epiphanius is harsh in his condemnation of them and asserts that the bottom line for the Alogi is that they deny the Gospel of John and consequently the Word-Flesh Logos doctrine. In Epiphanius, they are clearly distinguished from the Ebionites, and from the Docetists. Some have doubted their existence because of Epiphanius' seeming ability to exaggerate or multiply heresies.
- “Alogi,” in The Oxford Dictionary of the Christian Church, [ODCC] Edited by F. L. Cross. (New York: Oxford University Press, 1997), 45.
- “Alogi,” ODCC, 45.
- In particular Epiphanius traces their origin to Theodotus of Byzantium (Panarion 54.100.1).
- Philip Schaff, “Alogi” in A Dictionary of Christian Biography and Literature to the End of the Sixth Century A.D., with an Account of the Principal Sects and Heresies, by Henry Wace (Grand Rapids: CCEL, 2000), 34.
-  see also Philip Schaff, “Alogi” in Biographical Dictionary, 34.
- Epiphanius asserts in regard to the Alogi “for they themselves seem to believe as we do.”
- Gwynn, J. "Hippolytus and his “Heads against Gaius”," Hermathena, 6 (1888), 397-418.
- Bludau, A. Die Ersten Gegner der Johannes-Schriften (Biblische Studien, 22, Hefte 1 and 2; 1925).
- Fisher, G. P. "Some Remarks on the Alogi," Papers of the American Society of Church History, 2,1 (1890), pp. 1-9.
- Hall, S. G. "Aloger," in Theologische Realenzyklopadia 2. Edited by G. Krause, G. Muller, et al. Berlin: 1977 ff., 290-95.
- The Panarion of Epiphanius of Salamis: Book II and III, Translated by Frank Williams. Leiden: Brill, 1997. ISBN 90-04-09898-4.
- Rose, V. “Question Johannine. Les Aloges asiatiques et les aloges romains,” Revue Biblique 6 (1897): 516-34.
- Smith, J. D. Gaius and the Controversy over the Johannine Literature (PhD diss.), Yale University, 1979.
- Trevett, Chr. Montanism: Gender, Authority and the New Prophesy (Cambridge, 1996), pp. 29, 66, 138-41, 262-3.
- The article on the “Alogi” in Volume 1 of The Catholic Encyclopedia
- The article on the "Alogi" in The New Schaff-Herzog Encyclopedia of Religious Knowledge, 1:135.
- Catholic Encyclopedia: Montanists: Montanism in the West: "The old notion that the Alogi were an Asiatic sect (see ALOGI) is no longer tenable; they were the Roman Gaius and his followers, if he had any."