St. Irenaeus was born in Asia Minor about the year 140. It is not known when he came to Gaul. He was a priest of the Church of Lyons during the persecution of 177 when St. Pothinus, first bishop of the city and the first martyr of Lyons, was put to death. Irenaeus succeeded him as bishop and twenty-five years later, was martyred in his turn, during a fresh persecution. At a time when Gnostic sects threatened to undermine Christianity by a perversion of Christian thought, St. Irenaeus vigorously denounced all heresies and safeguarded unity of belief by laying down the principles of the doctrinal tradition of the Church.