Stalin took Pius XII’s encyclical [Orientales omnes ecclesias, on the Ukrainian Catholic Church] as a declaration of war, and he answered as was his wont: framing Pius XII as a Nazi collaborator. On June 3, 1945, Radio Moscow proclaimed that the leader of the Catholic Church, Pope Pius XII, had been "Hitler’s Pope," mendaciously insinuating that he had been an ally of the Nazis during World War II. Radio Moscow’s insinuation fell flat as a pancake … The Kremlin’s attempt to frame Pius XII as Hitler’s Pope was rejected by that contemporary generation that had lived through the real history and knew who Pope Pius XII really was. The Kremlin tried again in the 1960s, with the next generation, which had not lived through that history and did not know better. This time it worked.
It turns out it is a Nazi lie which is at the bottom of a claim that Pius XII was on their side.
The current charge claims that in a presentation Pius XII gave at an International Eucharistic Congress in Hungary in 1938—when he was still Eugenio Pacelli, Vatican Secretary of State—he referred to Jews as enemies of Christ and the Catholic Church.
Earlier attempts at smearing the Pope have been refuted, at least in the academy, but this looks like a smoking gun.
With the assistance of Vatican historian … Fr. Peter Gumpel, we reviewed the text of the speech as it was published in Discorsi e Panegirici. The quote as given by the critics does not appear therein. The ellipsis was used to link very diverse passages from different pages of Pacelli’s speech, producing a complete distortion of Pacelli’s words. … He referred to the masses that called for the Crucifixion and said they had been “deceived and excited by propaganda, lies, insults and imprecations at the foot of the Cross.” Those identified as enemies of Christ included Pontius Pilate, Herod, the Roman soldiers, the Sanhedrin, and their followers. He did not call out “all Jews” or “the Jews." About two pages later in the manuscript, Pacelli referred to those who were persecuting the Church at that time by doing things like expelling religion and perverting Christianity. Jews were not doing this, but Nazi Germany certainly was. The future pope was clearly equating the Nazis, not Jews, to those who persecuted the Church at earlier times.
It is not the KGB who are responsible for this one but some Nazi sympathisers in Hungary.
Where did the distorted quotation come from? The first use in English was by Herczl, in his Christianity and the Holocaust of Hungarian Jewry (1993). … Herczl was not present at the speech and did not even look at Pacelli’s script which can be found in Discorsi e Panegirici, a collection of Pius’s early writings first published in 1939, or even the Italian version that appeared in the Vatican newspaper. In his book, he cited a Hungarian newspaper, Nemzeti Ujsag (National Journal), with a long and controversial history as a political outlet. … The evidence is against Herczl. As its name implies and as numerous articles in the newspaper itself attest, Nemzeti Ujsag was a political journal, not a religious one. It was, at least in the relevant years, overtly anti-Semitic and truly despicable. Randolph L. Braham, a noted scholar in the field, called it a voice of National Socialism. … It is likely that the newspaper manufactured the quotation to support its anti-Semitic position. Pacelli, after all, was criticizing the exact political position the paper held. Then as now, Vatican support was a very useful thing to claim.
People would rather believe Communists or Nazis than the truth.