Tatian referred to himself as "an Assyrian," "born in the frontier district between the Roman Empire and Parthia". Trained in "mythology, history, poetry, and chronology" he became disgusted with paganism. He travelled first to Antioch and then to Rome, where he was converted by reading the Hebrew Scriptures. In Rome he joined the school of Justin Martyr, (between 150-165) whom he held in high regard. Tatian was a man of fiery temperament and seems to have found in Christianity a means by which to attack not only "pagan religion, but also the Roman system of law and government." He was apparently the first Christian writer to declare that God created matter by the power of the Logos: "And as the Logos, begotten in the beginning, begat in turn our world, having first created for Himself the necessary matter..." From this it was only a small step for later Christian thinkers to arrive at the doctrine of creation out of nothing. Unlike his teacher Justin he did not link the Greek hero Deucalion with Noah.
After Justins martyrdom Tatians teaching gradually became more and more ascetic, until he broke with the Church in about 172 and returned to Mesopotamia. Here (according to Eusebius and Jerome) he founded the sect of the Encratites. Who, it was alleged, abstained from meat and rejected worldly goods, substituting water for wine in the Eucharist. He was opposed by many of the early church fathers, including Irenaeus, Clement of Alexandria, Hippolytus and Origen. This probably explains why all but two of his numerous works have perished, so we have little opportunity to examine at first hand the claims of heresy levelled at him. Irenaeus summarises the false teachings of Tatian as follows:
Irenaeus notes that Tatian was the source of this last heresy. Robert M. Grant explains Tatians reasoning in the Address as follows: "...since immortality is obtainable only where a soul forms a union with the divine Spirit (13.2), and since the divine Spirit was lost by the same man (7.3), the first man Adam cannot have been saved." Perhaps more interesting than Tatians reasoning is the obvious inference that if Irenaeus was able to class the denial of Adams salvation as heresy (and Scripture is silent on this point) then the orthodox position at that time must have been that Adam was saved after the fall. It may well be that this doctrine was considered important because it countered Gnostic teaching to the contrary.
It is not surprising that Tatians teaching on creation was misinterpreted when he made use of Gnostic terminology. An example of this is Tatian's statement that the Logos, begotten by the Father, in turn 'begot' the creation (5.2). Further evidence of allegedly Gnostic teaching is found in Address 20:
The demons were driven forth to another abode; the first created human beings were expelled from their place: the one, indeed were cast down from heaven; but the other were driven from the earth, yet not out of this earth, but from a more excellent order of things than exists here now.
The phrase "not of this earth, but from a more excellent order of things..." may suggest to some a higher level of existence, but could equally be well be taken as a reference to the physical Eden, which is no longer part of this world. In defence of Tatian, Gerald F. Hawthorne has made the following points:
Given these considerations it is less easy to dismiss Tatian out of hand as a heretic. The charge that Tatian was a Gnostic is difficult to substantiate. Tatian clearly declared his belief in Christs incarnation, His suffering and bodily resurrection. We can only guess at the real reason for Tatians condemnation at the hands of Irenaeus. Some have suggested that it may have been his status as an independent Christian teacher. In such a position he was outside of the control of the church hierarchy and may well have been seen as a threat to orthodoxy; "orthodoxy" at that point in history being increasingly defined as that which the bishops believed.
 Tatian, Address, 42 (Ante-Nicene Fathers, Vol. 2, 81-82).
 Frend, The Rise of Christianity. (Augsburg Fortress Publishers, 1984), 175.
 Philip Schaff, History of the Christian Church, Vol. 2, 1910. (Grand Rapids: Eerdmans, 1989), 727.
 Tatian, Address, 29 (ANF, Vol. 2, 77).
 "Justin Martyr", Oxford Dictionary of the Christian Church 3rd edn., 1341.
 Tatian, Address, 18 (ANF, Vol. 2, 73).
 Frend, Rise, 175; Tatian, Address, 28 (ANF, Vol. 2, 77).
 B. Studer, "Creation," Angelo D. Bernardino, ed. Encyclopedia of the Early Church, Vol. 1. (Cambridge: James Clarke & Co., 1992).
 Tatian, Address, 5 (ANF, Vol. 2, 67).
 May, 154.
 Jack P. Lewis, A Study of the Interpretation of Noah and the Flood in Jewish and Christian Literature. (Leiden: E.J. Brill, 1968), 107: "Though Tatian does not specifically mention Noah's flood, his chronology would make it impossible for him to identify Deucalion with Noah (Address to the Greeks 39.2)."
 Eusebius, History, 4.29.3 (NPNF, 2nd series, Vol. 1, 208.
 Eusebius, History, 4.29.6 (NPNF, 2nd series, Vol. 1, 209); Jerome, Lives, 29 (NPNF, 2nd series, Vol. 3, 369); Against Jovinian 1.3 (NPNF, 2nd series, Vol. 6, 347); cf. Irenaeus, who writes that this sect came from Saturinus and Marcion (see Heresies 1.28.1 [ANF, , Vol. 1, 353]). Hendrik F. Stander, "Encratites," Encyclopedia of Early Christianity, 298.
 Stander, "Encratites," Encyclopedia of Early Christianity, 298.
 Clement of Alexandria, Stromata, 3.7; ANF, Vol. 2, 396, 406-407 (text in Latin).
 Hippolytus, Refutation, 8.9; 10.14 (ANF, Vol. 5, 122, 146).
 Oxford Dictionary of the Chriatian Church, 3rd edn., 1341.
 ANF, , Vol. 2, 61.
 Tatian rejected marriage on the basis of 1 Cor. 7:5 & Gal. 6:8; Tatian, Address, 8 (ANF, Vol. 2, 68); Irenaeus, Heresies 1.28.1 (ANF, Vol. 1, 353). See further R.M. Grant, "Tatian and the Bible," Kurt Aland & F.L. Cross eds. Studia Patristica, Vol. 1. (Berlin: Akademie-Verlag, 1957), 300-301.
 Irenaeus, Heresies, 1.28.1 (ANF, Series 1, Vol. 1, 353).
 Robert M. Grant, "The Heresy of Tatian," Journal of Theological Studies, Vol. 46 (1954): 64.
 Grant, "Heresy," 64.
 Grant, "Tatian," 305.
 Robert C. Newman, Personal Communication, November 1995.
 Gerald F. Hawthorne, "Tatian and His Discourse to the Greeks," Harvard Theological Review, Vol. 57, No. 3 (1964): 165-166.
 Eusebius, History, 4.29 (NPNF, 2nd series, Vol. 1, 207-209); Hippolytus, Philosphumena, 8.16.
 Eusebius, History, 5.13.1 (NPNF, 2nd series, Vol. 1, 227).
 Tatian, Address 21 (ANF, Vol. 2, 74).
 Tatian, Address 15 (ANF, Vol. 2, 71-72).
 Tatian, Address 13 (ANF, Vol. 2, 70-71).
|Clement of Alexandria, Miscellanies 3.12.81-82|
|Eusebius, Church History 4.16.7; 4.29; 5.13.8|
|H.G. Hogg, trans. "The Diatessaron of Tatian," Ante-Nicene Fathers, new edn., Vol. 10. Grand Rapids: Eerdmans, 1999. Hbk. pp.35-138.|
|Irenaeus, Against Heresies 1.28; 3.23.8|
|Origen, Against Celsus 1.16|
|Origen, On Prayer 24.5|
|Selections from the Prophetic Scriptures 36.|
|Tatian (Christian Classic Ethereal Library)|
|Tatian, The Earliest Life of Christ: The Diatessaron of Tatian, J. Hamlyn Hill (Translator). Gorgias Press, 2001. Pbk. ISBN: 0971309728.|
|Craig D. Allert, "The State of the New Testament Canon in the Second Century: Putting Tatian's Diatessaron in Perspective," Bulletin for Biblical Research 9 (1999): 1-18. pdf|
|T. Baarda, "John 1:5 in the Oration and Diatessaron of Tatian: Concerning the Reading katalambanei," Vigiliae Christianae 47.3 (1993): 209-225.|
|T. Baarda, "The 'Foolish' or 'Dead' Fig-tree Concerning Luke 19:4 in the Diatessaron," Novum Testamentum 43.2 (2001): 161-177.|
|George A. Barton & Hans Henry Spoer, “Traces of the Diatessaron of Tatian in Harclean Syriac lectionaries,” Journal of Biblical Literature 24.2 (1905): 179-195. pdf [This material is in the Public Domain]|
|G.W. Clarke, "The Date of the Oration of Tatian," Harvard Theological Review 60.1 (1967): 123-126.|
|F.L. Cross, The Early Christian Fathers. Studies in Theology 1. London: Gerald Duckworth & Co. Ltd., 1960. Hbk. pp.53-54, 66-68.|
|William John Ferrar [1868-1945], The Early Christian Books. Handbooks of Christian Literature. London: SPCK, 1919. Hbk. pp.108. pdf [This material is in the Public Domain]|
|Richard J.H. Gottheil, “Quotations from the Diatessaron,” Journal of Biblical Literature 11.1 (1892): 68-71. pdf [This material is in the Public Domain]|
|Isaac H. Hall, “A pair of citations from the Diatessaron,” Journal of Biblical Literature 10.2 (1891): 153-155. pdf [This material is in the Public Domain]|
|Gerald F. Hawthorne, "Tatian and His Discourse to the Greeks," Harvard Theological Review. Vol. 57 (1964): 161-188.|
|Roman Hanig, "Tatian und Justin. Ein Vergleich (Tatian and Justin: A Comparison)," Vigiliae Christianae 53.1 (1998): 31-73.|
|Peter M. Head, "Tatian's Christology and its influence on the composition of the Diatessaron," Tyndale Bulletin 43.1 (1992): 121-137. pdf|
|Tatian (Patrick J. Healy)|
|Emily J. Hunt, Christianity in the Second Century: The Case of Tatian. Routledge Early Church Monographs. London: Routledge, an imprint of Taylor & Francis Books Ltd., 2003. Pbk. ISBN: 0415304067. pp.256.|
|Edward A. Johnson, "The first harmony of the Gospels: Tatian's Diatessaron and its theology," Journal of the Evangelical Theological Society 14.4 (Fall 1971): 227-238. pdf|
|Jan Joosten, "Tatian's Diatessaron and the Old Testament Peshitta," Journal of Biblical Literature 120.3 (2001): 501-523.|
|Jan Joosten, "The Gospel of Barnabas and the Diatessaron," Harvard Theological Review 95.1 (2002): 73-96.|
|Tatian's Address to the Greeks (Peter Kirby)|
|Leslie McFall, "Tatian's Diatessaron: Mischievous or Misleading?" Westminster Theological Journal 56.1 (Spring 1994): 87-114. pdf [Accompanying tables: Table1a Table1b Table2]|
|Charles Marsh Mead, “Tatian’s Diatessaron and the analysis of the Pentateuch: a reply,” Journal of Biblical Literature 10.1 (1891): 44-54. pdf [This material is in the Public Domain]|
|Bruce M. Metzger, “Tatian’s Diatessaron and a Persian harmony of the Gospels,” Journal of Biblical Literature 69.3 (Sept. 1950): 261-280. pdf [Reproduced by permission of the current copyright holder]|
|George Foot Moore, “Tatian’s Diatessaron and the analysis of the Pentateuch,” Journal of Biblical Literature 9.2 (1890): 201-215. pdf [This material is in the Public Domain]|
|Nicholas Perrin, Thomas and Tatian: The Relationship Between the "Gospel of Thomas" and the "Diatessaron". SBL - Academia Biblica. Leiden: Brill, 2003. Hbk. ISBN: 9004127100. pp.218.|
|William L. Petersen, "New Evidence for the Question of the Original Language of the Diatessaron," Heinrich Greeven, ed., Studien zum TExt und zur Think des Neuen Testaments Festschrift... Berlin: de Gruyter, 1986. pp.325-343.|
|W.L. Petersen, "Tatian's Dependence upon Justin's APOMNHMONEYMATA," New Testament Studies 36 (1990): 512-34.|
|William L. Petersen, Tatian's "Diatessaron": Its Creation, Dissemination, Significance and History in Scholarship. Vigiliae Christianae Supplements Series. Leiden: Brill, 1994. Hbk. ISBN: 9004094695. pp.528.|
|Gilles Quispel, Tatian and the Gospel of Thomas: Studies in the History of the Western Diatessaron. Leiden: Brill, 1975. ISBN: 9004043160. pp.200.|
|Robert F. Shedinger, "Did Tatian Use the Old Testament Peshitta? A Response to Jan Joosten," Novum Testamentum 41.3 (1999): 265-279.|
|M. Whittaker, "Tatian's Educational Background," Studia Patristica 13 (1975): 57-59.|
|Edward J. Young, "Biblical Criticism in the Second Century" (Pd.D. diss., The Dropsie College for Hebrew and Cognate Learning, 1943). pdf [Reproduced by permission of the current copyright holder]|