Initially, Hitler cooperated with Catholic leaders
In 1933 he signed a Concordat with the Pope, so that they would not interfere with each other
But Hitler soon broke this agreement
He felt that German Catholics listened to the Pope more than him, so he harassed and arrested Catholic priests and closed down Catholic youth clubs and schools
Relations became so bad that in 1937 the Pope issued a statement called 'With Burning Anxiety', saying that the Nazis were 'hostile to Christ and his Church'
This was read out in Catholic churches across Germany, but it had little effect
The Nazis continued to arrest priests
In August 1941, one of Germany's best-known religious leaders, Catholic Archbishop Galen, openly criticised the Nazis for their terror tactics, euthanasia and concentration camps
As a result of his protests, Galen was put under house arrest until the end of the war