What was the main religion in Germany before the World War 2?

Answer 1

Christianity - Evangelical (Protestant) and Roman Catholic, very roughly in the ratio 9:10. with about 50% Protestants and 45% Roman Catholics

Lutheranism

There were very few Jews in Germany before WW2, at most 1% of the population. They were a tiny group, but visible because they tended to live in the larger cities, and played an important role in German cultural life, despite their insignificant numbers.

The southern areas of Germany and the Rhineland were mainly Roman Catholic, but most Northern Germans considered themselves Lutherans. The percentage of Catholics in Germany increased greatly after the 1938 Anschluss, when the nation of Austria merged with Germany, creating 'Greater Germany'. Austria was overwhelming Catholic which created problems for some Prussian Protestant German government officials.