In a three-day visit to Bulgaria and North Macedonia, Pope Francis appealed to Bulgarians to change their attitude towards migrants. While Bulgaria's orthodox church refused to hold joint services, a commemoration ceremony is planned on Tuesday in North Macedonia for Mother Teresa, who was a native of Skopje.
Pope Francis urged Bulgarians to open their hearts and doors to refugees as he began a visit to the European Union's poorest country.
The three-day tour, which also takes in North Macedonia, includes a visit to a refugee camp on the outskirts of Sofia and a commemoration of Mother Teresa, the most famous native of the Macedonian capital Skopje.
While the visit will be a particular highlight for the tiny Catholic communities in both countries - 44,000 people in Bulgaria and 20,000 in North Macedonia - it is the interaction with their two Orthodox churches that will be most keenly watched.
Bulgaria's declining population
In his first address to Bulgarian officials, the Pope evoked the "new winter" plaguing Bulgaria and other European nations facing an exodus as well as falling birth rates,
The population has now dropped to seven million as compared to nine million in 1989, the year communism ended in Bulgaria. It is projected to plunge to 5.4 million in 2050.
"Bulgaria faces the effects of the emigration in recent decades of over two million of her citizens in search of new opportunities for employment," he said, adding that this had "led to the depopulation and abandonment of many villages and cities".
Migrants: Pope evokes Bulgarian tradition of hospitality
Pope Francis also touched on the plight of migrants and refugees flocking to the country.
"Bulgaria confronts the phenomenon of those seeking to cross its borders in order to flee wars, conflicts or dire poverty, in the attempt to reach the wealthiest areas of Europe, there to find new opportunities in life or simply a safe refuge," the pope said.
"To all Bulgarians, who are familiar with the drama of emigration, I respectfully suggest that you not close your eyes, your hearts or your hands - in accordance with your best tradition - to those who knock at your door," he said.
Orthodox church rejects joint prayer
But last month the Bulgarian Orthodox Church's Holy Synod rejected the idea of Orthodox priests participating in a joint "prayer for peace" with the pope which had been planned for Monday.
The Orthodox Church is instead sending a children's choir to the downgraded meeting, which will be attended by at least one of the capital's Muslim leaders, a Vatican source said.
The Bulgarian church also made clear its opposition to any religious service when the pope visited Sofia's St Alexander Nevsky Cathedral. The Pope offered prayers there on Sunday afternoon alone.
It is the only Orthodox church not to participate in a commission fostering dialogue with the Roman Catholic church.