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Sister Mary Teresa Barron, an Irish missionary nun and superior general of the Missionary Sisters of Our Lady of the Apostles, is pictured in an undated photo. On Oct. 8, 2026, she was appointed to lead the Pontifical Mission Societies and serve as adjunct secretary of the Dicastery for Evangelization. She is the first woman to serve in those roles, which are effective Jan. 4, 2027. (OSV News photo/courtesy UISG)

Irish sister brings front-line missionary perspective to Vatican curial role


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Filed Under: Feature, News, Vatican, World News

(OSV News) — In accepting her dual appointment as head of the Vatican’s missionary network and as adjunct secretary at the Dicastery for Evangelization, Sister Mary Teresa Barron said it was clear the Church prioritized lived missionary experience over theological acumen.

In an interview with OSV News Oct. 9, the 57-year-old Irish nun said she was initially approached to be president of the Pontifical Mission Societies, before it was expanded to include serving as adjunct secretary of the dicastery’s Section for First Evangelization and the New Particular Churches.

“When I was asked, it was a mixture; it was excitement,” she said. “I’m a missionary, and just the thought of having that possibility of working at that level within the Church for the missionary animation of all the people of God was very exciting. On the other side of it, this was frightening because it’s a very big responsibility, with all the fears about what that entails.”

Referring to herself as a “very simple, basic missionary,” Sister Mary Teresa admitted that upon learning about her role at the dicastery, she asked herself, “Do I even have the qualifications for it?”

“I was assured that what was really being asked was to animate a missionary spirit,” she told OSV News. “I’ve been a missionary for 34 years — my whole essence is being a missionary. If it’s about putting a missionary spirit into something, I certainly can offer that. But in terms of a theological background, I don’t have the academic qualifications. I was assured that wasn’t what was being looked for at this point.”

Since 2018, Sister Mary Teresa has led the Missionary Sisters of Our Lady of the Apostles as superior general, a post she must step down from before assuming her new role at the Vatican in January.

“All of that brought very mixed emotions, but it was really exciting and, of course, humbling to be even considered and asked to take on the role,” she said.

— United in mission —

A native of Donegal, Ireland, Sister Mary Teresa’s missionary experience focused on pastoral work in Africa, including in Nigeria and Tanzania.

According to Vatican News, she also held several major leadership positions, serving as president of the Service of Documentation and Study on Global Mission from 2022 to 2025, as well as president of the International Union of Superiors General, or UISG, in Rome from 2023 to 2025.

Yet, for Sister Mary Teresa, her understanding of religious vocation and evangelization was “a gradual process” that began at the start of her missionary work.

“Very early on in my missionary life, I accompanied a young Tanzanian mother who was dying from AIDS,” she told OSV News. “She held a traditional view, believing that sickness was a punishment from God. Accompanying her and helping her see that wasn’t the case — that God loved her and that she was united with Christ suffering on the cross — was a defining moment for me.”

“I remember my leader at the time said to me, ‘Maybe that’s what God wants you in this world for: just to be there for that woman.’ It really brought home to me that mission is about the relationship with the person beside you. It’s not about big gestures,” she added.

Reflecting on the theme of the upcoming 100th World Mission Sunday, “One in Christ, united in mission,” the Irish nun said that, ultimately, “the essence of mission is love,” and she understood that in her roles as superior general of her congregation and leading the UISG.

“I always questioned God: ‘Why are you asking me to do these things?'” she recalled. “Then last November, at a school in northern Nigeria, our children and some of our staff were kidnapped. In that moment, it was a ‘God moment.’ It was like, ‘Now I know why I have been in these positions — because I had so many connections around the world, and so many people prayed for those children and that staff.'”

Calling that particular experience “another moment of gradually trusting in God day to day,” Sister Mary Teresa told OSV News that the kidnapping was “a powerful experience for our congregation of the solidarity and prayer from around the world.”

— Missionary rule: Just listen, watch and learn for first 6 months —

Pope Leo XIV’s familiarity with the challenges, hopes, and fears missionaries face, due to his experience as an Augustinian missionary in Peru spanning over two decades, has informed his way of leading the Church, which Sister Mary Teresa noted is “very rooted in the reality of what is going on in the world.”

“It is very exciting that he is a missionary,” she said. “I don’t know the man particularly well, but from what I see and witness, he is a great listener. He knows what it’s like to walk beside people who are suffering and challenged, and understands the need to simply be there, accompanying and seeing what we can do together.”

The pope’s repeated calls for peace since his 2025 election, she added, exemplified the missionary quality of being “very much rooted where you are.”

“We always say as missionaries: for the first six months, do nothing. Just listen, watch, and learn. That is always good advice — to be respectful of other cultures and perspectives,” Sister Mary Teresa said.

— Seeing God’s dream clearly —

As the first woman to lead the Pontifical Mission Societies, Sister Mary Teresa was among several women Pope Leo appointed to important curial roles this year. The Irish nun recalled receiving messages from around the world “acknowledging the need to have women at all levels of leadership within the Church because it brings such a different perspective.”

Nevertheless, the reality of her appointment hit home at the dicastery office after the announcement, with Filipino Cardinal Luis Antonio Tagle, pro-prefect of the Dicastery for Evangelization; Nigerian Archbishop Fortunatus Nwachukwu, secretary of the dicastery’s missionary section; and Msgr. Samuele Sangalli, who also serves as adjunct secretary.

“I was struck by the reality: I am the first woman standing here with these men, sitting at the table,” she told OSV News. “Even some of the staff said to me that it is so good to have the female perspective because together we can see better what God’s dream is.”

That female perspective, she added, “is so important.”

“It is still minimal, but we are getting there step by step,” Sister Mary Teresa said. “Beyond the high-profile roles, many women are involved throughout the dicastery, offering their perspectives. It is very hopeful.”

She recalled participating in the 2023-2024 Synod of Bishops on synodality as one of 54 women present as voting members. “That was a small percentage, but significant to be sitting at the table and having our voices heard,” she said.

— In God’s time —

One issue at the forefront of the synod’s discussions was the role of women in the Church, including the possibility of ordaining women deacons.

While acknowledging that it is a “very complex area” with “so many dimensions to it,” Sister Mary Teresa told OSV News that in the Church, “women religious and many laywomen are deeply committed and do so much.”

“People talk about supporting the Church, but for me, the Church is in the service of God’s mission,” she said. “There are women all around the world who are seriously committed to that in their day-to-day engagement.”

Synodality, she added, has given the Church “the opportunity to listen together to God’s spirit,” which “takes time.”

“The beauty of the Catholic Church is our diversity; we have a broad spectrum of perspectives, and communion is essential,” Sister Mary Teresa said. “We want to move together without breaking the Church.”

“What is painful for some people is that change takes a long, long time,” she added. “But we do what we are called to do for our time, and trust that God’s plan will evolve when the time is right — in God’s time.”

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