Theological Contribution
In his five-volume work against the heresies, Irenaeus answered the Gnostic teachers of his age, above all Valentinus and Marcion, who divided the God of creation from the God of redemption and disparaged the material world. Against them he insisted on the unity of God, the goodness of the creation, and the reality of the Incarnation, by which the Son of God took on human flesh born of a Virgin.
He is remembered as an early and influential witness to apostolic succession, holding that the unbroken line of bishops from the Apostles safeguarded the true teaching of the Church. He was also among the earliest writers to regard the four gospels together as the foundational Scripture, and he developed the theme of recapitulation, in which Christ as the new Adam reverses the disobedience of the first Adam through his own obedience.
The Paschal Controversy
When the Roman bishop Victor pressed for uniform observance of the date of Pascha and his demands threatened to divide the Church, Irenaeus wrote in the name of the Christians of Gaul to Victor and to others, urging that peace be kept between the communities of Asia and Rome. His intervention is remembered for its appeal to reconciliation rather than rupture, fitting for a bishop whose very name means 'peaceful'.
Relics & Shrines
Irenaeus was buried beneath a church in Lyons dedicated to Saint John, which was later renamed in his own honor. His tomb and remains were destroyed in 1562 during the Wars of Religion, when Calvinist forces sacked the church. Relics associated with him survive in Lyons; a heelbone preserved in the cathedral has been radiocarbon-dated to a period consistent with his lifetime.
Veneration
Irenaeus is venerated across the ancient Christian traditions as a Father of the Church. Orthodox usage commemorates him on August 23, while other calendars keep his memory on June 28. As a bishop who died for the faith, he is honored in the Orthodox Church with the rank of hieromartyr.
