CERDONIANS, a Gnostic sect, founded by Cerdo, a Syrian, who came to Rome about 137, but concerning whose history little is known. Most of what the Fathers narrate of Cerdo's tenets has probably been transferred to him from his famous pupil Marcion; like whom he is said to have rejected the Old Testament and the New, except part of Luke's Gospel and of Paul's Epistles. (See MARCION AND THE MARCIONITE CHURCHES; also GNOSTICISM.)