Pope Francis said on Thursday that he plans to declare St. Irenaeus of Lyon a Doctor of the Church with the title “Doctor unitatis,” meaning “Doctor of Unity.”

The pope made the announcement in a speech to the St. Irenaeus Working Group, a group of Catholic and Orthodox theologians who conducted a study together on synodality and primacy.

“Your patron, St. Irenaeus of Lyon -- whom soon I will willingly declare a Doctor of the Church with the title Doctor unitatis -- came from the East, exercised his episcopal ministry in the West, and was a great spiritual and theological bridge between Eastern and Western Christians,” Pope Francis said on Oct. 7.

St. Irenaeus was a second-century bishop and writer revered by both Catholics and Orthodox Christians and known for refuting the heresies of Gnosticism with a defense of both Christ’s humanity and divinity.

The U.S. bishops voted last year in favor of having St. Irenaeus named a Doctor of the Church at the request of Cardinal Philippe Barbarin, the then archbishop of Lyon, southern France, and sent their approval to the Vatican for the pope’s consideration.

Pope Francis previously declared St. Gregory of Narek, a 10th-century Armenian monk, a Doctor of the Church in 2015.

Benedict XVI named Sts. John of Avila and Hildegard of Bingen as Doctors of the Church in 2012.

Seventeen of the 36 figures declared Doctors of the Church by the Catholic Church lived before the Great Schism of 1054 and are also revered by Orthodox Christians.

St. Irenaeus would be the first martyr to be receive the title.

“His name, Irenaeus, contains the word ‘peace,’” Pope Francis said. “We know that the Lord’s peace is not a ‘negotiated’ peace, the fruit of agreements meant to safeguard interests, but a peace that reconciles, that brings together in unity. That is the peace of Jesus.”

The pope spoke about synodality and primacy during his meeting with the St. Irenaeus Working Group, a joint Orthodox-Catholic working group from the Institute for Ecumenical Studies at the Pontifical University of St. Thomas in Rome.

“A fruitful approach to primacy in theological and ecumenical dialogues must necessarily be grounded in a reflection on synodality. There is no other way.” Pope Francis said.

“I have frequently expressed my conviction that in a synodal Church, greater light can be shed on the exercise of the Petrine primacy.”

Petrine primacy refers to the absolute authority of the pope as a pastor and governor with immediate and direct jurisdiction over the whole Church.

The primacy of the Bishop of Rome is one of the major issues of disagreement that has kept Orthodox Christians apart from the Catholic Church. The Eastern Orthodox have a conciliar model of the Church, rather than a centralized authority.

Pope Francis thanked the group for its recently issued study, “Serving Communion: Re-thinking the Relationship between Primacy and Synodality.”

“Through the constructive patience of dialogue, especially with the Orthodox Churches, we have come to understand more fully that in the Church primacy and synodality are not two competing principles to be kept in balance, but two realities that establish and sustain one another in the service of communion,” the pope said.

“Just as the primacy presupposes the exercise of synodality, so synodality entails the exercise of primacy.”

Pope Francis expressed hope that the Catholic Church’s upcoming synod on synodality will allow Catholics around the world to reflect on synodality and Petrine primacy.

The pope will kick off the Church’s three-year synodal process this weekend with a Mass on Oct. 10. All dioceses have also been invited to offer an opening Mass the following Sunday on Oct. 17.

“I am confident that, with the help of God, the synodal process that will begin in the coming days in every Catholic diocese will also be an opportunity for deeper reflection on this important aspect, together with other Christians,” Pope Francis said.

Pope Francis noted that the group of Orthodox and Catholic scholars had chosen St. Irenaeus as their patron.

“Dear friends, with the help of God, you too are working to break down dividing walls and to build bridges of communion,” he added.

Cardinal Kurt Koch, the president of the Pontifical Council for Promoting Christian Unity, also participated in the papal audience with the St. Irenaeus working group.

The cardinal has argued that strengthening synodality is “the most important contribution” that the Catholic Church can make to ecumenical dialogue, especially dialogue with the Orthodox.

“This synod will not only be an important event in the Catholic Church, but it will contain a significant ecumenical message, since synodality is an issue that also moves ecumenism, and moves it in depth,” Koch wrote in the Vatican newspaper L’Osservatore Romano on Jan. 18.

He pointed to the 2007 Declaration of Ravenna, in which Catholic and Orthodox theologians agreed that the bishop of Rome was the “protos,” or first among patriarchs, before the separation of East and West.

“The fact that the two dialogue partners were able to declare together for the first time that the Church is structured synodally at all levels and therefore also at the universal level, and that she needs a protos is an important milestone in Catholic-Orthodox dialogue,” he said.

For this step to bear fruit in the future, Koch wrote, it is necessary to deepen the relationship between synodality and primacy.