The Argentine pontiff is due in the southern city of Lund for an ecumenical service marking the start of a year of celebrations for the 500th anniversary of the Reformation.
The event will also mark 50 years of reconciliatory dialogue between the Catholic Church and Lutheranism, a tradition that was once fervently hostile to the authority and teachings of the Vatican. Just by agreeing to attend, Francis has made a gesture that would have been unimaginable for all but his most recent predecessors.
“We were very surprised” when he said he wanted to come, Anders Arborelius, Bishop of the Catholic Church in Sweden, told The Local and other journalists at a press conference in Lund on the eve of the Pope's visit, but added that he was very pleased.
— Emma Löfgren (@ekjlofgren) October 30, 2016
The popes of the 16th century spent huge amounts of time and energy trying to stifle or reverse the reforming wave launched by the German monk Martin Luther when he nailed his '95 theses' to the door of a church in Wittenberg on October 31st, 1517.
Ahead of the visit to Sweden, Francis went out of his way to underline that Catholicism no longer regards Luther, who was excommunicated, as a heretical figure.
“Luther took a great step by putting the words of God into the hands of the people,” Francis was quoted by the AFP as telling two Jesuit publications, in an apparent reference to the monk's efforts to get a German translation of the Bible printed and circulated.
Some Catholic conservatives, however, question whether there is anything about the Reformation worth celebrating.
Partly for that reason, every word of the sermon the ever unpredictable Francis delivers in Lund is likely to be closely scrutinized, as will remarks by Mounib Younan, the Palestinian president of the World Lutheran Federation.
The pontiff's body language will also be closely watched, particularly when he is led into the Lund cathedral by Antje Jackelén, the female archbishop who is the senior cleric in the Swedish Lutheran Church.
With its approval of women holding office, backing for gay marriage and openly lesbian and gay bishops, the Swedish Church is liberal to an extent unimaginable for the vast majority of Catholic clerics.
— The Local Sweden (@TheLocalSweden) October 25, 2016
The two traditions also differ in their approach to church governance – hierarchical for Catholicism, flat for the Lutherans – as well as on more esoteric theological questions.
But they also share many religious customs, such as baptism, and Younan told AFP that he would like to see Catholics and Lutherans authorized to take communion together – something currently ruled out by Vatican doctrine.
“We are praying that one day we may celebrate the holy communion together, this is very important for me,” Younan said, while stressing the importance of accentuating common ground.
“In this time when extremism is devouring all the world globally, we are giving an example to the whole world that this is a common commemoration despite our disagreement in the past, a sign of unity and a sign that religion is no more a problem,” he said.
Monday's programme also includes an event in a stadium in Malmö that will be addressed by the bishop of the besieged Syrian city of Aleppo. It will conclude with a mass prayer for peace in the war-torn country.
The charity wings of the two churches are also due to seal a cooperation accord.