In Germany, churches can collect taxes from their members. This is called the church tax (Kirchensteuer). Around half of German tax payers pay the church tax1. The church tax is 8% of your income tax in Bavaria and Baden-Württemberg, and 9% in the rest of Germany.
If you had to do that as a token of your faith, to attend services, mariages and burials, would you?
It is easy to tick 'C of E' or other faith on the census- another to put your money where your tick is.
I've got another 'keen'... Ouch!