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.
