Well, the state collects the tax for the churches ... at least for the two major ones roman catholic and lutheran - I'm not sure about others. You get asked for your religion the first time you apply for a tax card and if you want to change it later you have to pay a fee (unless you are a student).

It's kind of weird. Although we don't have a legal seperation of religion and state, people tend to be less religious or at least less obvious about their religion than people in N-America. On the other hand we still have religiously influenced laws like shops usually have to be closed on Sundays and holidays, and no dancing or loud music on certain christian holidays.