The distinguished German theologian, Jürgen Moltmann, has spoken of his concern about the resurgence of nationalism around the world.
Moltmann, who served in the Hitler Youth and was a WWII POW at the time of his conversion to Christianity, called the new wave of nationalism taking root in many countries a "setback for humanity".
"Humanity precedes nationality," he said in a lecture to students at the World Council of Churches' Ecumenical Institute at Bossey, Switzerland.
The 93-year-old spoke candidly about growing up under the "extreme nationalism" of Nazi Germany and the impact this had on his own family.
"In my youth, I lived in extreme nationalism, patriotism and the Nazi dictatorship," he recalled.
"When Hitler came into power in Germany in 1933, I was seven years old. My larger family was divided in anti-Hitler socialists and pro-Hitler Nazis."
As a young boy, he says he did not enjoy the militarism of the Hitler Youth but took part because he "was a patriot".
Then in 1937, his father was told to either join the Nazi party or lose his job as a teacher. He joined the party to save his family's life and then, when the War broke out, volunteered for the army, but internally, he remained at odds with Nazism.
"During World War II, he had said: 'Hitler must not win this war.' He also said, 'A man must defend his fatherland.' He couldn't solve this contradiction," Moltmann said.
"He returned in 1946 out of French prisoner-of-war camps."
Before the War was over, Moltmann himself would be drafted into the German Army along with his entire school class at just 16. He would go to spend three years in British prisoner of war camps.
After the War ended, he said he returned home to Germany in 1948 feeling "lost over Auschwitz and the killing of German soldiers by the SS".
"Since then, I have been convinced there is no fatherland in dictatorship," he said. "My love for Germany is constitutional patriotism."
He challenged Christians to reject nationalistic ideas.
"The church of Christ is present in all the people on earth and cannot become 'a national religion'," he said.
"The church of Christ ecumenically embraces the whole inhabited earth. She is not a tribal religion, nor a Western religion, nor a white religion, but the church of all humanity."
He added: "The church of Christ is not national, but it is a church of all the nations and humanity."