Pope Francis is to hold a mass on Tuesday for the Catholic minority in Sweden, a Lutheran but secular country where same-sex marriage is allowed even for priests.

The Argentine pontiff, on the second and last day of his trip to Sweden, will address the crowd inside a large stadium in the southern Swedish town of Malmo at 9:30 am (08:30 GMT).

An expected 24,000 members of the country's Roman Catholic minority are set to attend, many of them converts or migrants. 

A fervent advocate of Christian unity, Francis visited the southern city of Lund on Monday for an ecumenical service marking the start of a year of celebrations for the Reformation -- the dramatic 1517 event that created a Protestant branch of Christianity which rebelled against papal rule.

The event in Lund, where the Lutheran World Federation was founded in 1947, also marked 50 years of reconciliatory dialogue between the Catholic Church and Lutheranism, a tradition once fervently hostile to the authority and teachings of the Vatican.

Together with Sweden's female archbishop Antje Jackelen and other Lutheran leaders, the Pope expressed deep regret over the conflict between Catholics and Protestants during Christianity's schism five centuries ago, calling for unity.

Hailed as "a breath of fresh air" by Swedish Lutheran leaders, Francis raised hopes early in his papacy that he might steer the church towards greater acceptance of homosexuality, and in June he said Christians "must apologise" to gays and lesbians for their past treatment. 

Anders Arborelius, bishop of the Roman Catholic Church in Stockholm, however said the pope's approach has been one of continuity, despite a "progressive" image compared to his predecessors.

"Pope Francis comes from another continent and has a different way of expressing things, but one cannot say that he has changed anything in the teachings," he told AFP.

Sweden's branch of the Lutheran Church is amongst the most liberal in Christendom, and the pope's visit highlights deep splits between the Vatican's doctrine and Swedes' way of life.

A pioneer in women's and LGBT rights, the Nordic nation's Lutheran church has been appointing female priests since 1960, a step the Catholic church is still reluctant to take. 

Figures released in 2010 showed that 45 percent of Sweden's nearly 4,500 professional priests were female, with the proportion even higher among parish priests. 

- 'Tainted by atheism' - 

The Swedish Lutheran church says it currently has 6.2 million members, more than 60 percent of the nation's population. But as fewer Swedes believe or practise religion -- and refuse to pay a tax collected for religious groups -- the church has also lost more than 550,000 of its members in 10 years.

Agneta Sofiadotter, a 62-year-old artist in Lund, was born to a Lutheran family but converted to Catholicism because she felt the Swedish church had given up on the community and holy rituals, tainted by atheism.

"I was terrified over the members of the Swedish church not even praying together for their work," Sofiadotter told AFP. 

"In the Catholic assembly there is a constant community prayer... one prays together with the church leader," she said.

"It is clear that you get an incredible longing for a communion with God," she added.  

- Triggered by immigration -

On the other hand, Catholicism is on the rise in Sweden. The Church now has 113,000 members (1.1 percent of the population) compared with only 87,000 in 2000, but it says it believes the actual number of Catholics in the country to be 150,000.

Even bishop Anders Arborelius was born into the Lutheran church but later converted to Catholicism.

Referred to as "The Church of the converts", the Swedish Catholic Church in recent years has seen a 3-4 percent annual increase in members, mainly triggered by immigration, church registrar Louis Michel told AFP. 

Historically, immigrants have mainly come from war-torn countries such as present-day Syria and Iraq, Lebanon in the 80s, and Latin America in the 60s and 70s, according to Michel.

Source: AFP