A great many Lutheran and Catholic clergymen were persecuted, imprisoned and killed for opposing Hitler, the great Lutheran pastor and writer Dietrich Bonhoeffer is probably the best known.
Individuals saints and martyrs notwithstanding, the official Churches did not oppose the regime openly. Yet there is no comparison.
No Church suffered more than the Russian Orthodox Church. Patriarch Tikhon, and his locum tenens, refused to submit to the regime of Vladimir Ilyich Lenin. By 1924, faced with pogroms unseen and unparalleled anywhere in the 20th century, Tiikhon's locum tenens finally signed a paper under duress promising to cease resisting the regime (at that time, Pat. Tikhon was exiled).
What kind of a duress? Well between 1927 and 1940, the number of Orthodox churches in the Russian Soviet republic declined from 29,584 to less than 500, or 98.3%!
Tens of thousands of Russian Orthodox priests and bishops were arrested and executed. Estimates vary, but almost all of them hover between 98 to 120 thousand. I am sure no other Church in Europe has suffered as much.
It is nauseating to read about the "collaborationist" Orthodox Church in the USSR by members of west European Churches which, overall, lived in great harmony with the Nazi and Fascist regimes during World War II, from Franco's Spain and Mussolini's Italy, to Nazi Germany. After all, young Ratzinger did not serve with distinction in Hitler Jugend, but he did not resist it actively either, certainly not enough to be arrested or to cause his parents to be arrested.
Catholic Church and Protestant communities acted in their own interest in Nazi Germany and elsewhere in Fascist Europe. By comparison, the number of Catholic priests, mostly from Poland, as individual martyrs, who died in Nazi concentration camps 2,800 along with 289 nuns.
It is a historical fact that the Catholic Church looked favorably on Hitler's party in 1933 as a barrier to spread of communism.
In that same year, the Catholic Church signed an agreement with Hitler's regime to stay out of politics. Sure sounds like open collaboration to me. No different than the patriarchal locum tenens signed in the Soviet Union. But the Orthodox are "collbaorationists," while the Catholic Church is not?!? Especially given the fact that this was done under no duress!
Pope Pius XI issued his "Mit brennender Sorge" not over the treatment of the Jews but over Hitler's arrest of of some activist Catholic clergy. But the Church as a whole was never sacked.
The treatment for he clergy and the churches in a large part depended on where the churches were located and whether the clergy belonged to "inferior" Slavic race, the case of Polish priests already having been mentioned, and whether the Slavic population was supportive (Ukraine, Croatia) or opposed (Poland, Czechoslovakia, etc.) to the Nazis.
Nürenburg documents show that the Church in Czechoslovakia, especially the Orthodox Church, but Catholic and Protestant communities as well, were actively persecuted, while in Fascist Croatia the Catholic Church was not just tolerated but favored and highly visible and cooperating with the regime in forcibly converting scores of Orthodox Serbs to catholicism, thereby implementing Ante Pavelich's tripartite "solution" to the Serbian question (convert one third, exile one third, exterminate one third).
As many as 3,000 Czechoslovak Catholic priests were arrested and some 700 killed as early as 1941. Still, as terrible as these figures are, they do not represent a Church-wide persecution by the Nazi regime, but a political one in select areas.
The Church as a whole was not brutalized if it collaborated with the Nazi regime. The fact that the Catholic Church survived Nazi Germany and even in places like Poland is indicative of no systematic campaign to destroy the Church.
In short, there is simply no comparison to the suffering endured by the Russian Orthodox Church and her clergy, and there is no question that the Catholic Church and Protestant communities collaborated with the Nazis. In view of the historical facts, neither Catholics nor Protestants have any moral right to criticize the Russian Orthodox Church as "collaborationist" except as an extreme form of hypocrisy and outright ignorance.