Overview
Cerdo was a Syrian Gnostic who was deemed a heretic by the Early Church around the time of his teaching, circa 138 AD. Cerdo started out as a follower of Simon Magus, like Basilides and Saturninus, and taught at about the same time as Valentinus and Marcion. According to Irenaeus, he was a contemporary of the Roman bishop Hyginus, residing in Rome as a prominent member of the Church until his forced expulsion therefrom.
He taught that there were two gods, one that demanded obedience while the other was good and merciful. According to Cerdo, the former was the God of the Old Testament who had created the world. He also said that the latter God was superior but that he was only known through his son, Jesus. Like later Gnostics, he was a docetist who rejected the bodily resurrection of the dead.
Doctrine
According to the account of Irenaeus (i. 27 and iii. 4), Cerdo had not the intention of founding a sect apart from the church. He describes him as more than once coming to the church and making public confession, and so going on, now teaching his doctrine in secret, now again making public confession, now convicted in respect of his evil teaching, and removed from the communion of the brethren (aphistamenos tes ton adelphon synodias). Some understand this to mean that Cerdo voluntarily withdrew himself from communion, but it is preferred to understand the word passively, with the old translator of Irenaeus, "abstentus est a religiosorum hominum conventu."
The account given by Irenaeus of the doctrine of Cerdo is that he taught that the God preached by the law and the prophets was not the Father of Jesus Christ; for that the former was known, the latter unknown; the former was just, the latter good. The account given by Pseudo-Tertullian (Haer. vi.) may be regarded as representing that given in the earlier Syntagma of Hippolytus, which was also made use of by Philaster (Haer. 44) and Epiphanius (Haer. 41). It runs that Cerdo introduced two first principles (archai) and two gods, the one good, the other evil, the latter of whom was the creator of the world. Here we are to note the important difference that to the good god is opposed in the account of Irenaeus a just one; in that of Hippolytus, an evil one. In the later Refutation of Hippolytus, Cerdo is said to have taught three principles of the universe, agathon, dikaion, hylen.
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