In an address the day after he was elected pope in 2005, Benedict XVI pledged to work for the unity of all the followers of Christ, saying that good sentiments were not enough and concrete deeds were needed.
Some were sceptical about the German-born pope’s ecumenical commitment given his reputation as the Vatican's doctrinal enforcer in his previous position as head of the Congregation for the Doctrine of the Faith.
Yet he was the first pope to have come from a country with a roughly equal balance between Protestants and Catholics, and one that had been at the very centre of the 16th century Reformation.
Benedict was also the first pope to have belonged to a committee of the World Council of Churches, as one of the Catholic members of its Faith and Order Commission.
In Germany he had been part of a working group of Protestant and Catholic theologians that sought to find ways of bridging the centuries-old rift between the two traditions.
At the Vatican, he is said to have played a decisive role in the 1999 joint declaration by the Catholic Church and the Lutheran World Federation on justification, one of the central issues in the 16th century that divided the followers of Martin Luther and the papacy.
After becoming pope, however, Benedict seemed at times to follow a policy of one step forward and one step back in reaching out to Protestants.
In 2011, he became the first pope since the Reformation to visit the Augustinian monastery - now a Protestant church - in the German city of Erfurt where Luther trained as a monk. At a meeting there with Protestant leaders, Benedict praised Luther’s lifelong quest to understand how to receive the grace of God.
However, at the service that followed this meeting, he disappointed many in Germany by announcing he had not brought with him an “ecumenical gift” - understood to be a reference to a widespread desire for mixed Protestant-Catholic couples to be able to receive communion together.
Benedict’s invitation in 2012 to Dr Rowan Williams to become the first archbishop of Canterbury to address a synod of bishops in Rome said something of the pontiff’s appreciation for the Anglican leader. However, the Vatican’s decision to set up an “ordinariate” to receive disaffected Anglicans led to widespread irritation.
It was with the Orthodox churches of the east to which most hopes for greater unity were directed. Within a short time of Benedict becoming pope, long-standing grievances that had prevented meetings of the Catholic-Orthodox dialogue commission were swept aside.
By 2007, the commission had drawn up the “Ravenna declaration” as a first step towards overcoming the thousand-year disagreement on the role of the papacy.
Intriguingly, several key individuals in this process had all been members of the WCC’s Faith and Order Commission. Alongside Benedict, they included the two co-presidents of the Orthodox-Catholic dialogue commission, Cardinal Walter Kasper, and Orthodox Metropolitan John Zizioulas, as well as Ecumenical Patriarch Bartholomeos I, the “first among equals” of the Orthodox world.
Still, the early momentum was lost in the years that followed, in part because of disagreements between Orthodox churches themselves.
Nevertheless, one of the possibly unintended consequences of Benedict’s announcement that he is to step down as pope - something unprecedented in the modern era - is that it might set in motion a dynamic that creates renewed opportunities for ecumenical dialogue by offering a new perspective on the role and place of the papacy.
© Stephen Brown is a former managing editor of Ecumenical News International (ENI) in Geneva. He is an Ekklesia associate, and has reported from many international church gatherings over the past 25 years.