That's an excellent question, especially since it's asked of a religious leader of millions. Here's a line from another book (which I haven't read nor own) that seems to ask the same question you do...
"If the Catholic Church is merely considered as a political institution that has to calculate the outcome of its decisions in terms of instrumental rationality, then Pius's choice may be deemed reasonable in view of the risks entailed. If, however, the Catholic Church also represents a moral stand, as it claims, mainly in moments of major crisis, and thus has to move on such occasions from the level of institutional interests to that of moral witnessing, then of course Pius's choice should be assessed differently."From "The Years of Extermination: Nazi Germany and the Jews, 1939-1945" by Saul Friedlander:
Not that excuses an individuals shortcomings, but did any Christian Churches really step up to stop the Nazis?