Obama speaks at landmark Berlin Christian convention

Thousands of people cheered when Barack Obama took to the stage in front of the Brandenburg Gate on Thursday. The former US president participated in a public discussion that was part of the Protestant "Kirchentag," or Church Day, in Germany's capital.

At the event celebrating the 500th anniversary of the Reformation, Obama spoke with German Chancellor Angela Merkel about how to "shape democracy and take responsibility at home and in the world." Some of Merkel's political opponents have criticzed the event as a publicity stunt set up to boost her popularity ahead of Germany's parliamentary elections in September.

Obama is a lot more popular in Germany than his successor Donald Trump. The thousands of visitors who wanted to see the former president had to go through tight security checks. In addition to police on the ground, helicopters patrolled the skies and snipers were camped out on the roofs of nearby buildings.

Obama praised Merkel as a leader who had done "outstanding work." He went on to talk about the rise of nationalism and xenophobia in many western countries and said that "we have to push back against those trends that would violate human rights or suppress democracy or restrict individual freedoms."

Obama also highlighted the need for liberal democracy and diplomacy. Members of the audience held up signs that made it clear they would have preferred a third Obama term to Trump's current policies. While the former president did not refer to the current one directly, he said to the cheering crowd that "we can't isolate ourselves. We can't hide behind a wall."

The discussion between Obama and Merkel was hosted by Kirchentag President Christina Aus (pictured). Obama has said in previous years that he considered himself a "devout Christian." When discussing refugee policies on Thursday, he said that a child on the other side of a border deserved just as much love as his own in the eyes of God.

The Kirchentag marks Obama's eighth visit to Germany. His first to Berlin took place during his first presidential race. In July 2008, the then-presidential candidate gave a foreign policy speech at the Victory Column in front of an enthusiastic crowd of 200,000 people. Long before anyone had ever heard of a US surveillance scandal, many young Germans were enamored with Obama.