Robert Barron, bishop-elect of the Diocese of Winona-Rochester, celebrated the feast day of St. Irenaeus Tuesday.

“St. Irenaeus, pray for us!” the diocese posted online.

St. Irenaeus was born to a Greek family in Asia Minor around the year 120, according to Britannica. He encountered St. Polycarp, the last living connection to Jesus' Apostles, before Polycarp was martyred in 155.

He served as a missionary and peacemaker before becoming bishop of Lugdunum in 177, Britannica says. Irenaeus wrote extensively and spent much of his life combatting heresies and trying to make peace between different factions. For example, when the Roman church and the churches of Asia Minor disagreed over the date on which Easter should be celebrated, Irenaeus mediated between the two and emphasized that the difference was insignificant and should not disturb their unity.

In January of this year, Pope Francis announced that he would bestow the title of Doctor of the Church upon St. Irenaeus, according to Vatican News. The pope described Irenaeus as “a great spiritual and theological bridge between Eastern and Western Christians.”

“Doctor of the Church” is an official title that a pope can bestow upon a person who has made significant and lasting contributions to the church, according to the Crossroads Initiative. Throughout the history of the Catholic Church, only 36 people have ever been granted this title. There are three requirements to becoming a Doctor of the Church: “holiness that is truly outstanding, even among saints”; “depth of doctrinal insight”; and “an extensive body of writings which the church can recommend as an expression of the authentic and life-giving Catholic Tradition.”

Irenaeus is the patron saint of catechists and apologists, according to My Catholic Life.