Tatian of Adiabene, or Tatian the Syrian,Tatian the Assyrian, (/ˈteɪʃən, -iən/; Latin: Tatianus; Ancient Greek: Τατιανός; Syriac: ܛܛܝܢܘܣ; c. 120 – c. 180 AD) was a Syrian Christian writer and theologian of the 2nd century.
Tatian's most influential work is the Diatessaron, a Biblical paraphrase, or "harmony", of the four gospels that became the standard text of the four gospels in the Syriac-speaking churches until the 5th-century, after which it gave way to the four separate gospels in the Peshitta version.
Concerning the date and place of his birth, little is known beyond what Tatian tells about himself in his Oratio ad Graecos, chap. xlii (Ante-Nicene Fathers, ii. 81–82): that he was born in "the land of the Assyrians"; (referring to Syria) Tatian was not born in geographical Assyria (Mesopotamia), he was born to the west of the Euphrates (Syria) scholarly consensus is that he died c. 185 AD, perhaps in Adiabene.
He traveled to Rome, where he first encountered Christianity. During his prolonged stay in Rome, according to his own representation, his abhorrence of the pagan cults sparked deep reflections on religious problems. Through the Old Testament, he wrote, he grew convinced of the unreasonableness of paganism. He adopted the Christian religion and became the pupil of Justin Martyr. During this period Christian philosophers competed with Greek sophists. Like Justin, Tatian opened a Christian school in Rome.