In his 1942 Christmas statement, broadcast over Vatican Radio, Pius said that the world was “plunged into the gloom of tragic error,” and he spoke of the need for mankind to make “a solemn vow never to rest until valiant souls of every people and every nation of the earth arise in their legions, resolved to bring society, and to devote themselves to the services of the human person and of a divinely ennobled human society.” He said that mankind owed this vow to “the hundreds of thousands who, through no fault of their own, and solely because of their nationality or race, have been condemned to death or progressive extinction.” He urged all Catholics to give shelter wherever they could. In making this statement and others during the war, Pius used the Latin word stirpe, which means race or nationality, but which had been used for centuries as an explicit reference to Jews.
British records reflect the opinion that “the Pope’s condemnation of the treatment of the Jews & the Poles is quite unmistakable, and the message is perhaps more forceful in tone than any of his recent statements.” […]
The Pope’s Christmas message was not hard for the Axis leaders to decipher. The German ambassador to the Vatican complained that Pius had abandoned any pretense at neutrality and was “clearly speaking on behalf of the Jews”. One German report stated:
In a manner never known before, the Pope has repudiated the National Socialist New European Order….[H]is speech is one long attack on everything we stand for…God, he says, regards all people and races as worthy of the same consideration. Here he is clearly speaking on behalf of the Jews…he is virtually accusing the German people of injustice toward the Jews, and makes himself the mouthpiece of the Jewish war criminals.”
Lt. Gen. Ion Mihai Pacepa and Professor Ronald Rychlak, Disinformation: Former Spy Chief Reveals Secret Strategies for Undermining Freedom, Attacking Religion, and Promoting Terrorism (2013)