St. Irenaeus was born in Asia Minor, probably around the year 125. 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.
As bishop of Lyons he was especially concerned with the Gnostics, who took their name from the Greek word for “knowledge.” Claiming access to secret knowledge imparted by Jesus to only a few disciples, their teaching was attracting and confusing many Christians. After thoroughly investigating the various Gnostic sects and their “secret,” Irenaeus showed to what logical conclusions their tenets led. These he contrasted with the teaching of the apostles and the text of Holy Scripture, giving us, in five books, a system of theology of great importance to subsequent times. Moreover, his work, widely used and translated into Latin and Armenian, gradually ended the influence of the Gnostics.
O God, who didst bestow upon blessed Irenaeus, thy Martyr and Bishop, grace to overcome false doctrine by the teaching of the truth, and to establish thy Church in peace and prosperity: we beseech thee; that thou wouldest give thy people constancy in thy true religion; and grant us thy peace all the days of our life; through Jesus Christ thy Son our Lord, who liveth and reigneth with thee, in the unity of the Holy Spirit, ever one God, world without end. Amen.