FILE PHOTO: U.S. President Barack Obama speaks during his last press conference at the White House in Washington, U.S., January 18, 2017. REUTERS/Joshua Roberts

BERLIN (Reuters) - Former U.S. President Barack Obama will join German Chancellor Angela Merkel in Berlin in May as part of celebrations to mark 500 years of Protestantism in Europe, officials said on Tuesday.

They will discuss “shaping engaged democracy and taking responsibility at home and in the world” in front of the historic Brandenburg Gate, the officials with Germany’s Protestant church said.

The May 25 meeting is being organised by a church group and Obama’s charitable foundation.

It will be a centrepiece of the biennial gathering of the church, which is this year focusing on commemorations of the Reformation, launched in 1517 when Martin Luther posted his 95 Theses on the door of Wittenberg Cathedral.

Obama’s visit to Germany will also coincide with a NATO summit in Brussels on May 25, which his successor Donald Trump plans to attend.

Heinrich Bedford-Strohm, who heads the Protestant church in Germany, sharply criticised Trump in February when he imposed a travel ban on people from some majority-Muslim countries.

“President Barack Obama’s participation ... on a joint stage with the Chancellor ...underscores how internationally we are celebrating 500 years of the Reformation,” Bedford-Strohm said in a statement. “Those who are pious must also be political.”

Church officials said they expected more than 100,000 people to participate in the gathering which will take place in both Berlin and Wittenberg from May 24-28.

A crowd of more than 200,000 turned out to hear the then presidential candidate Obama speak in Germany in July 2008.