The Roman Catholic Church suffered persecution in Nazi Germany. The Nazis claimed jurisdiction over all collective and social activity. Clergy were watched closely, and frequently denounced, arrested and sent to Nazi concentration camps. Welfare institutions were interfered with or transferred to state control. Catholic schools, press, trade unions, political parties and youth leagues were eradicated. Anti-Catholic propaganda and "morality" trials were staged. Monasteries and convents were targeted for expropriation. Prominent Catholic lay leaders were murdered, and thousands of Catholic activists were arrested.

The Reichskonkordat is a treaty negotiated between the Vatican and the emergent Nazi Germany. It was signed on 20 July 1933 by Cardinal Secretary of State Eugenio Pacelli, who later became Pope Pius XII, on behalf of Pope Pius XI and Vice Chancellor Franz von Papen on behalf of President Paul von Hindenburg and the German government. It was ratified 10 September 1933 and it has been in force from that date onward. The treaty guarantees the rights of the Catholic Church in Germany. When bishops take office Article 16 states they are required to take an oath of loyalty to the Governor or President of the German Reich established according to the constitution. The treaty also requires all clergy to abstain from working in and for political parties. Nazi breaches of the agreement began almost as soon as it had been signed and intensified afterwards leading to protest from the Church including in the 1937 Mit brennender Sorge encyclical of Pope Pius XI. The Nazis planned to eliminate the Church's influence by restricting its organizations to purely religious activities.