After his trip to the Middle East, Pope Francis has again chosen difficult terrain for his next foreign visit. Catholicism may be booming in South Korea, but under North Korea's totalitarian regime, Christians are systematically persecuted. And in China, officials recently announced plans to create their own version of Christian theology – one that is acceptable to the state.

This papal visit is not just about reaching out to South Korean Catholics, but rather Catholics across all of East Asia. The official purpose of the trip is for the pope to attend the sixth Asian World Youth Day, which is expected to attract up to 6,000 participants, a third of whom are coming from abroad.

Christians in Asia have waited a long time for such a high profile visit from the Vatican: The last papal visit to the continent took place 13 years ago, and the last visit to South Korea was more than 25 years ago. But at the beginning of his papacy, Pope Francis stated that Asia would be a special focus of his.

Model country

South Korea is one of the Catholic Church's big success stories. The positive image of the church and the growth in membership there serve as a contrast to the declining numbers of Catholics in many Western countries. Catholicism and Christianity are still relatively new in South Korea, with a history dating back around 230 years. The first religious texts entered the country via laypeople who had come into contact with Christians in Beijing.

When the first foreign priest went to South Korea at the end of the 18th century, he found a congregation of 4,000 believers. The Catholic Church experienced a further boom following World War II and the Korean War. In recent years, the number of Catholics has grown ten-fold while the general population of the country has merely doubled. Today, one in every 10 South Koreans professes to be Catholic, and 30 percent of the country's population is Christian. After the Philippines, South Korea is the second-strongest Christian nation in Asia.

The trend shows no sign of stopping: Each year, more than 100,000 adults are baptized in South Korea. Many of these new Catholics are from the upper classes and reside in cities. The church continues to enjoy a high level of recognition and trust, because during the time of the military dictatorships until the end of the 1980s, it remained a critical opponent of the regime.

Persecution of Christians

Christians suffered all manner of persecution in the 18th and 19th centuries. Around 10,000 Christians from that era are remembered as martyrs. During his first visit to Korea, Pope John Paul II canonized 103 of these martyrs. Pope Francis will beatify a further 124.

On the first day of the papal visit, protocol and political appointments will dominate the agenda. South Korean President Park Geun-hye will officially welcome the pope, who will then deliver a speech to a group of politicians. On the second day of his trip, Pope Francis will celebrate a mass for participants of the Asian World Youth Day in the World Cup stadium in Daejeon.

Before he leaves, he will also meet with other religious leaders, and celebrate a mass of reconciliation in Seoul's main cathedral. Catholics from North Korea were invited to attend the mass, but Pyongyang rejected the offer. Originally, the pope had planned to visit the demarcation line between North and South Korea, but this has been cancelled as it could have been seen as a provocation by the North Korean regime.

Still, the pope is expected to send a clear message to Pyongyang about the situation of Christians in North Korea. And as he has proved in the past, Pope Francis is always good for a surprise. During his Middle East visit, for example, he spontaneously invited the presidents of Israel and the Palestinians to come to Rome to pray together.