Gnostic heretic, active at Rome in the mid-2nd c. According to Irenaeus Adv. haer. I, 27,1, Cerdo arrived in the capital under Pope Hyginus 138 142 and there taught heretical doctrines, according to which the creator God, just and knowable, revealed in the law of Moses and the Prophets, is distinguished from the Father of Jesus Christ, good and unknowable. Still, according to Irenaeus Adv. haer. III, 4,3, Cerdo, agreeing to do penance and feigning repentance, was initially restored to the community but secretly continued to spread his teachings; again found guilty, he was finally definitively excluded from the community. This information, and a link of Cerdo with the Simonian heresy, are substantially confirmed by Hippolytus Ref. VII, 10,37; X, 19, who depends on Irenaeus. Irenaeus’s attribution to Cerdo of the main doctrines of Marcion, whom he makes merely Cerdo’s disciple and continuator, with no originality of his own, seems more suspect and may be the result of a confusion, perhaps in Irenaeus’s sources, or of an error in relating the list of the bishops of Rome to the appearance of individual heretics in the capital see Harnack and Peterson. Epiphanius Pan. XLI, 1 and Filaster Haer. 44 say that Cerdo was a native of Syria. Epiphanius attributes docetist doctrines to him; ps.-Tertullian Adv. omnes haer. 6 even attributes Marcion’s NT canon to him. According to Agapius Universal History, in PO VII, 511, Cerdo stated that the world was created by various divinities coming together, and denied the resurrection. A. Harnack, Marcion. Das Evangelium von fremden Gott, Leipzig 1924 Beilage II: Cerdo und Marcion, 31-39; G. Bardy, DHGE, 12 1953, col. 162-163; E. Peterson, Cerdone: EC III, 1313-1314; J. Quasten, Patrologia, vol. I, Turin 1975, 237; G. May, Markion und der Gnostiker Kerdon, Evangel. Glaube und Geschichte, Festschrift G. Mecenseffy, Vienna 1984, 233-284; R.J. Hoffmann, Marcion and the Restitution of Christianity, Chico, CA 1984, 41-44; BBKL III, 1384-1385 1992.