The Church is composed of sinful people who make mistakes. Repent. Turn to God. These must always be heard for the Church to be the Church.
Italy and Spain, dominantly Catholic countries, had allied with Germany during WWII. This could not have happened if large numbers of the Catholics in those 3 countries had not deserted Catholic ideals. The faith needed to be reasserted strongly, so that atrocities like that could not be repeated by Christians.
The mass exodus from the Church began much earlier, when the Church presented herself as socially stratified, with some more equal than others, and demanded unthinking obedience and lockstep behavior. Seing those same attitudes twisted by the Nazis demanded a change of heart, and a change of how the faith is presented.