This is to open up any misunderstanding about the Catholic Church role during WWII.
I like to start by quoting a tract from Catholic Answers Online.
How Pius XII Protected Jews
By Jimmy Akin
The twentieth century was marked by genocides on an monstrous scale. One of the most terrible was the Holocaust wrought by Nazi Germany, which killed an estimated six million European Jews and almost as many other victims.
During this dark time, the Catholic Church was shepherded by Pope Pius XII, who proved himself an untiring foe of the Nazis, determined to save as many Jewish lives as he could. Yet today Pius XII gets almost no credit for his actions before or during the war.
Anti-Catholic author Dave Hunt writes, “The Vatican had no excuse for its Nazi partnership or for its continued commendation of Hitler on the one hand and its thunderous silence regarding the Jewish question on the other hand. . . . [The popes] continued in the alliance with Hitler until the end of the war, reaping hundreds of millions of dollars in payments from the Nazi government to the Vatican.”
Jack Chick, infamous for his anti-Catholic comic books, tells us in Smokescreens, “When World War II ended, the Vatican had egg all over its face. Pope Pius XII, after building the Nazi war machine, saw Hitler losing his battle against Russia, and he immediately jumped to the other side when he saw the handwriting on the wall. . . . Pope Pius XII should have stood before the judges in Nuremberg. His war crimes were worthy of death.”
One is tempted simply to dismiss these accusations, so wildly out of touch with reality, as the deluded ravings of persons with no sense of historical truth. This would underestimate the power of such erroneous charges to influence people: Many take these writers at their word.
Stepping out of the nightmare fantasyland of Hunt and Chick and back into sunlight of the real world, we discover that, not only was Pius XII no friend of the Nazis, but that his opposition to them began years before the War, before he was elected to the papacy, when he was still Cardinal Eugenio Pacelli, the Vatican Secretary of State.
On April 28, 1935, four years before the War even started, Pacelli gave a speech that aroused the attention of the world press. Speaking to an audience of 250,000 pilgrims in Lourdes, France, the future Pius XII stated that the Nazis “are in reality only miserable plagiarists who dress up old errors with new tinsel. It does not make any difference whether they flock to the banners of social revolution, whether they are guided by a false concept of the world and of life, or whether they are possessed by the superstition of a race and blood cult.” It was talks like this, in addition to private remarks and numerous notes of protest that Pacelli sent to Berlin in his capacity as Vatican Secretary of State, that earned him a reputation as an enemy of the Nazi party.
The Germans were likewise displeased with the reigning pontiff, Pius XI, who showed himself to be a unrelenting opponent of the new German “ideals”—even writing an entire encyclical, Mit Brennender Sorge (1937), to condemn them. When Pius XI died in 1939, the Nazis abhorred the prospect that Pacelli might be elected his successor.