SUDBURY — One freezing winter day when he was a child, Cardinal Sean P. O’Malley told a congregation of Catholics and Methodists Sunday afternoon, the pipes in his house burst and his father opened the phone book to find a plumber.
O’Malley’s mother sang out, “Be sure you call a Catholic!”
These days, O’Malley said, the split between Catholics and Protestants has been replaced with a “new polarity . . . between believer and nonbeliever,” a shift that should spur Christians to greater cooperation.
Christians also share a common enemy, he added: what Pope Francis has called “the globalization of indifference” to those who are poor and suffering.
“The call to unity is an imperative,” O’Malley said.
The cardinal was preaching at a special service at Sudbury United Methodist Church in honor of the 50th anniversary of Cardinal Richard Cushing’s historic visit to the same congregation to discuss the Second Vatican Council’s work on ecumenism, or efforts toward Christian unity. Bishop Sudarshana Devadhar of the New England Conference of the United Methodist Church also presided at the service, along with the Rev. Joel B. Guillemette, pastor of the host church, and the Rev. Richard Erikson, pastor of Our Lady of Fatima Parish in Sudbury.
The service fell on the Sunday on which many Christians celebrate the baptism of Jesus. After the homily, O’Malley and Devadhar received congregants one by one, making a sign of the cross on their foreheads with water, telling each, “Reaffirm your baptism and be thankful.”
“It was wonderful to get both congregations together,” said Jim Carleton, a member of Our Lady of Fatima, at a reception after the service. “We could have more of this, really.”
Cushing’s trip to the Sudbury church, at the height of council’s work toward modernizing the Roman Catholic church and forging improved relationships with other Christians and faiths, was a remarkable event at a time when Protestants and Catholics often regarded one other with suspicion and rarely entered one another’s houses of worship.
A Globe story published after Cushing’s visit called it “the most remarkable hour and a half ever experienced by church people in the old town.” A photo caption marveled: “In the congregation, you could not tell which were Protestants and which Catholics.”
“I think of what he did in Sudbury as something similar to what Nixon did when he went to China — it was real detente,” said Guillemette. “Doors were opening, and that all came out of Vatican II.”
The Second Vatican Council marked a major shift in the Catholic church’s posture toward other Christians, said Richard Gaillardetz, the Joseph Professor of Catholic Systematic Theology at Boston College and president of the Catholic Theological Society of America. The tenor, he said, went from one of “we’re right, you’re wrong, come back to us,” to one of dialogue.
“The council decided instead of focusing on areas where there is disagreement between Catholics and other Christians, they would focus first on all the things Christians had in common,” he said in a telephone interview.
The council also recognized that errors were made on both sides of the divisions between Catholics and other Christians and declared that the Roman Catholic church has the obligation to adopt a more self-critical attitude. And, Gaillardetz said, it stated that the church, as a human institution, will always be in need of reform and renewal.
Cushing, who had earlier on that Sunday in 1964 presided at a memorial Mass for President John F. Kennedy, arrived in a black stretch limousine, extending his hand to the first person he met as he walked in: “My name’s Cushing. . . . What’s yours?”
He charmed his audience, describing his upbringing in “tough’’ South Boston, what a poor student he’d been, and how he loved Pope John XXIII, the reform-minded pontiff who called the Second Vatican Council.
Cushing said the reunification of Christian churches could take hundreds of years, but in the meantime, “we have unity of the spirit of love.”
Beverly Paro, 81, a member of the Methodist church who was there that day and attended the service with O’Malley Sunday, too, remembers how Cushing had the large crowd laughing. “I think he put everyone at ease,” she said.
Cushing’s visit, which came at the invitation of the Sudbury UMC church’s then-pastor, the Rev. Blaine Taylor, became a point of pride for the church, which has built a tradition of interfaith and ecumenical work.
Guillemette heard about it soon after he became pastor in 2006, and found himself mentioning it in a sermon last year on a text from John 17, in which Jesus prays “that they might all be one.”
Afterward, he said, it occurred to him that Erikson, pastor of Our Lady of Fatima in Sudbury, had served as a top archdiocesan official under O’Malley. The two were already friendly; they’d gotten to know each other through the town’s close-knit interfaith clergy group. Guillemette sent Erikson the sermon, and the two sent O’Malley a letter describing the Cushing visit and inviting the archbishop to Sudbury.
Guillemette, who was raised Baptist, remembers the coldness between many Catholics and Protestants during his childhood. When the Baptist church in Lowell burned down, he says, a nearby Catholic parish took up an offering to help their neighbors rebuild.
“The Baptists sent it back,” he said. “That’s the world I grew up in. Building bridges between Catholic and Protestant Christians is important to me.’’
Today, although high-level talks among Christian theologians and prelates continue, divisions over doctrine, sacraments, and, particularly, structures of ministry and leadership remain. There are also disagreements over social issues, such as homosexuality and contraception. And, in the past decade, the Catholic church has had to focus intensively on its internal strife over the abuse crisis.
“It is officially a part of everyone’s effort, but it is not at the top of the priority list for a lot of people,” said the Rev. Raymond Helmick, a theologian at Boston College.
Yet interdenominational — and interfaith — marriages, along with religiously diverse neighborhoods and workplaces, have become the norm.
Local churches continue to collaborate in efforts to serve the poor in their communities, and in many communities, including Sudbury, interdenominational and interfaith clergy groups are strong.
“I think many Christians are waiting for Christian institutions to catch up to the unity they already experience on the local level,” said the Rev. Laura Everett, executive director of the Massachusetts Council of Churches, the state’s main ecumenical organization.
There is some evidence of a growing interest in developing those interchurch relationships.
A number of noteworthy events will mark the Week of Prayer for Christian Unity next week, including a joint service with the bishop of the New England Synod of the Evangelical Lutheran Church in America and the bishop of the Episcopal Diocese of Western Massachusetts.
O’Malley will preside at a service at the Basilica of Our Lady of Perpetual Help in Boston honoring martyrs from different Christian communities; the heads of many churches have been invited to attend.
“The strength of the movement toward Christian unity is deepening because of our long effort to build contacts and trust,” said Vito Nicastro, associate director of the archdiocese’s Office for Ecumenical and Interreligious Affairs.
Many church observers say Pope Francis’ emphasis on the core values of Christianity, rather than divisive social issues, and his call to care for people on the margins have galvanized Christians.
“He’s another John XXIII,” said Janet Johnson, 79, a member of the Sudbury United Methodist Church, of Francis. “My heart soars when I hear Francis talk about how we must be concerned about the poor, the least of these.”
Correction: Because of a reporting error, the name of Richard Gaillardetz, the Joseph Professor of Catholic Systematic Theology at Boston College and president of the Catholic Theological Society of America, was misspelled in an earlier version of this article.