The Archbishop of Canterbury, Pope Francis and the Church of Scotland Moderator, the Revd Martin Fair, have written to South Sudan's political leaders to urge them to continue seeking peace.
South Sudan gained independence from Sudan in 2011 but got embroiled in a civil war in December 2013. The country's president, Salva Kiir, and opposition leaders signed a peace deal in 2018 and agreed to form a unity government.
However localised conflicts have continued, there are warnings of a severe famine because of fighting and Covid-19 and many regions have been affected by flooding.
The Pope and the Archbishop of Canterbury have shown particular interest in peace in South Sudan before. At the request of Pope Francis, Archbishop Justin Welby led a spiritual retreat for South Sudan's senior political and church leaders at the Vatican in April 2019.
At the end of the trip, Pope Francis knelt before the leaders of South Sudan and the opposition, kissed their shoes and urged them to pursue peace. "Remember that with war, all is lost," the Pope said.
The two religious leaders then announced in November 2019 that they intended to make a joint visit to South Sudan, which has not yet been possible.
This Christmas they have signed a joint letter where they welcome the "small progress" the leaders have made but say it is "not enough" for the people of South Sudan.
They remind the political leaders of their commitments made at the Vatican in April 2019 to bring South Sudan to a smooth implementation of the Peace Agreement. They also restate their commitment to making a joint visit to the country.
The heads of the Catholic Church and Church of England write: "We remain prayerfully mindful of the commitments made at the Vatican in April 2019 - yours to bring your country to a smooth implementation of the Peace Agreement, and ours to visit South Sudan in due course, as things return to normalcy."
"We have been glad to see the small progress you have made, but know it is not enough for your people to feel the full effect of peace. When we visit, we long to bear witness to a changed nation, governed by leaders who, in the words of the Holy Father last year, 'hold hands, united... as simple citizens' to 'become Fathers (and Mothers) of the Nation'."
They add: "We pray, this Christmas, that you will know greater trust among yourselves and a greater generosity of service to your people. We pray you know the peace that surpasses understanding in your own hearts and in the heart of your great nation (Philippians 4:7)."