The mark its centenary, the German Catholic Congress is heading east. Only 4.3 percent of Leipzig's 570,000-strong population is Catholic - that's less than 20,000 believers. Nearly three times as many people in Saxony's trade fair city are Protestant. But the vast majority - 80 percent - is unaffiliated to any religion. Such a large Christian gathering is therefore quite the challenge for Leipzig, for Catholics and non-believers alike. While Catholics lead a procession through the city on Thursday to celebrate the feast of Corpus Christi, many a Leipziger will most likely just be wondering what's going on.

The Catholic Congress is set to pose the "great questions of human existence" - questions which concern everyone, Christian believer or not. "I see the chance to speak with people in a secularized environment as a great opportunity at this event," said Leipzig's Mayor Burkhard Jung. "At the 1994 Catholic Congress in Dresden, attempts at discussion didn't work out. More than two decades later, however, the challenge in Leipzig is still exciting, particularly given the volatile situation in the city and the state of Saxony.

Of course, a great number of German political figures are set to descend upon Leipzig, including German President Joachim Gauck, and a number of federal ministers from the SPD and the CDU/CSU Union. Several state premiers - among them, Baden-Württemberg's Catholic Green Party member, Winfried Kretschmann - will also be attending. That's all part of it. But much of the Congress in Leipzig will happen on a rather smaller scale, with meetings also held on the outskirts of town. With more than 1,000 events listed in the 640-page program booklet, the offering is barely manageable.

German President Joachim Gauck will be attending the Congress in Leipzig

The approach to the religious and basic human question lies in the motto of Congress: "Behold the man." The phrase is taken from the words of Pontius Pilate in the Passion of the Christ: "Ecce Homo". Bearing the motto in mind, the respect of human dignity and humanity in times of modernity will be the main focus point of the event.

The five-day Congress, therefore, aims to continue the tradition of Catholic laity by also addressing society. The hundredth gathering marks 168 years of the Congress in Germany and 168 years of cooperation and conflict between the state and the church.

The story of the German Catholic Congress began in Mainz in 1848 - the year in which the German National Assembly first met in Frankfurt's Paulskirche and the year Karl Marx published the Communist Manifesto.

At that time, were Catholics faced the harsh controls of the state. Between 1932 and 1948 there was no German Catholic Congress. After rising to power in 1933, the Nazis demanded an oath of allegiance only to the "Führer." It's only since the 1950s - with a few exceptions - that the Catholic Congress has taken place every two years - alternating with the Protestant Church Congress.

"Behold the man" is the motto for the 2016 German Catholic Congress

The meetings reflect a history of political and social Catholicism: a search for identity at the beginning, then social and socio-political participation, and, in recent decades, even ecclesiastical infighting. To this day, Catholic Congresses are considered to be a "Festival of the Congress" and a "Faith Day," as well as a snapshot and mirror image of the Catholic Church in Germany. In its earlier days, politically, the events were shaped exclusively by the Union. Meanwhile, however, the climate has relaxed, with politicians from the Greens, the FDP, and the Left also attending.

But there'll be no sign of Alternative for Germany (AfD). The subject has been discussed countless times in recent months. The right-wing populist party seems to be anchored in eastern Germany. As a result of the Dresden-based xenophobic PEGIDA demonstrations, which also sympathize with the AfD, no other German state is facing as much criticism for its political stance that Saxony. The Central Committee of German Catholics (ZdK) already decided months ago that no top AfD representatives would be invited to the podiums of the German Catholic Congress.

CDU politician and ZdK President Thomas Sternberg has called for reforms

Amid the ongoing debate over the AfD's religious hostility, criticism for the decision has died down in recent days. The question of a social division will be breached nonetheless.

One thing is clear, however: After the one hundredth Catholic Congress, it won't just be "business as usual." In a bookmarking the anniversary of the German Catholic Congress, President of ZdK, Thomas Sternberg, has called for reflection and reform. In light of the ever-declining number of Catholics in Germany, forums such as the Congress are necessary, Sternberg said. But it's also worthwhile "working on reforms to adapt the Catholic Congress to the time."