Monk Martin Luther nailed to the door of church in the German town of Wittenberg on Oct. 31, 1517 a document with 95 arguments against what was going wrong in the Catholic Church at the time.
His act triggered a series of history changing events along with the Protestant Reformation and centuries of bloodletting and persecution between Catholics and Protestants in different countries.
But on Oct. 31, 2016 in southern Sweden something remarkable will happen.
An ecumenical service attended led by Pope Francis and leaders of the Lutheran World Federation in a joint commemoration of the Reformation on 31 October 2016 in Lund, Sweden.
Along with Francis, Bishop Munib Younan, LWF president and Rev. Martin Lund, the general secretary of the federation will lead the service.
King Karl XVI Gustav and Queen Silvia of Sweden will attend the service.
The Monday service will be the first time in living memory that a prayer service organized jointly by Catholics and Lutherans at the global level is being held in the Cathedral in Lund.
For local Lutheran and Catholic leaders, the thousands of practical details needed to prepare for the event do not diminish the personal and potential local impact on the churches.
'DREAM COME TRUE'
"It's been a long-standing dream of mine that different traditions in the churches can show a greater respect for one another. This meeting is therefore a dream come true," says Johan Tyrberg, Lutheran Bishop of the Diocese of Lund since 2014.
"It's all about ending a conflict that has lasted for 500 years," Tyrberg noted. "The last 50 years we have been discussing how to make peace.
"It is in this spirit that the leaders of the Catholic and the Lutheran Church are meeting in Lund. It is an important step and part of the process of reconciling with the past and moving forward together."
Dominican Father Johan Lindén of St. Thomas Aquinas Church and Catholic parish in Lund, said, "The joint commemoration will offer an opportunity to grow in the understanding of the reformation, to understand what happened then and what the consequences are today. We share a common heritage and history."
He told a Church of Sweden interviewer the hope is that future generations can reap what is now being sowed for renewed initiatives, a deeper understanding and more respect for the differences in Catholic and Lutheran traditions.
As one of the two local Catholic coordinators, Lindén notes, "It is also mutual opportunity to repent, to convert ourselves and ask for forgiveness. The mutual and clear exchange of forgiveness is what the whole event implies and signals.
"What we have seen in the past few years is that Pope Francis is putting a lot of effort into the ecumenical dialogue with other Christian churches and denominations. The [quest] for unity is very apparent in his pontificate. This is close to Pope Francis' heart."
LA CIVILITA CATTOLICA
Ahead of his trip to Sweden, Pope Francis granted a lengthy interview to the editor of the Swedish Jesuit magazine, Fr. Ulf Jonsson, that was carried in the journal La Civiltà Cattolica.
Francis noted how at the beginning of the Reformation Martin Luther's intention when he nailed his 95 theses to the church door was to reform in a "in a difficult time for the Church."
"Luther wanted to remedy a complex situation," said the Pope, explaining that the gesture "also because of the political situations... became a 'state' of separation, and not a process of reform of the whole Church, which is fundamental, because the Church is semper reformanda (always reforming)."
When it comes to Scripture, the Pope said Luther did an important thing by putting the Word of God into peoples' hands, adding that "reform and Scripture are two things that we can deepen by looking at the Lutheran tradition."
In Sweden the humanitarian and development arms of the Lutheran World Federation and the Catholic churches will make a new commitment to responding together to human need throughout the world.
The Lutheran World Federation's World Service and Caritas Internationalis will participate in the Joint Catholic-Lutheran commemoration of the reformation in Lund and Malmö on Oct. 31.
Caritas and LWF World Service will sign a Declaration of Intent, with the objective to strengthen the collaboration of the two organizations, both of which engage strongly in humanitarian work and with refugees.
"Diakonia or service is an area where we have already and continue to be able to find each other easily. It is a central calling to all Christians," LWF World Service Director Maria Immonen said.
"Our joint action unites and gives a deeper meaning to the slogan 'Together in hope'. We work together, side by side, as we are called to do. It is outward looking – the face of the church to the world at large and open to collaboration with each other as well as other actors working for justice and peace."