It is more tax avoidance than anything else combined with Germans getting poorer. In Germany if you are an official member of a religion then the German government taxes you and then “gives” it to your religion. The German fascists have found a way to make people naturally pissed off at the churches because of the taxes.
The “church tax” has been in place for many, many years.
Oh, Muslims are tax exempt.
Every single German Catholic that I know has given Vater Staat and the church the one finger salute and left the church.