We didn’t oppose the fascists when the moment came because we heard they were going to lose

The encyclical was issued Spring 1937. Well before it was obvious the Nazis were going to lose. This also pre-dates events like the Kristallnacht.

This papal encyclical was not the first word against Nazism. It came after growing criticism of Nazism:

• In 1933, the Bishop of Münster, Clemens August Graf von Galen, publicly criticized the Nazis’ policies, particularly their treatment of the mentally ill.

• The German bishops issued a pastoral letter in 1934 that condemned the Nazi regime’s violations of human rights.

• Going back to 1922, GK Chesterton famously condemned what was brewing in Germany when he wrote “Eugenics and other Evils.”

You have to keep in mind that the Nazis used a new idea of science to create eugenics to justify much of their evil and this new science was at odds with Catholic teaching. Catholic teaching was perceived at the time as old, backward, superstitious, and an impediment to progress. To them, progress required the genocide of lesser people to make room for a superior race. The idea that God would become man and that man was a Jew was repulsive to these men.

This was an era of extremes. Nazism on one side and Communism on the other. The Church did not suddenly come to the right stance at the end of the war. They came to that stance as the evil arose and increased their opposition to it as the degree of evil became more apparent. Mit brennender Sorge represented a real risk to Catholics in Germany … a risk worth taking because the evil of the Nazis had grown significantly.