Irenaeus (/ɪrɪˈneɪəs/; Greek: Εἰρηναῖος Eirēnaios; c. 130 – c. 202 AD) was a Greek bishop noted for his role in guiding and expanding Christian communities in what is now the south of France and, more widely, for the development of Christian theology by combating heresy and defining orthodoxy. Originating from Smyrna, he had seen and heard the preaching of Polycarp, the last known living connection with the Apostles, who in turn was said to have heard John the Evangelist.