The final one, as if reading my mind, said that even if I'd been baptised in another country, being in the church was a "worldwide membership". This is a bit ridiculous, because in England there's no church tax.
Yes, in Germany, you sometimes have to leave the church, even if you are not part of the church.
Having heard a few horror stories - or perhaps urban myths is a better way to describe them - I wanted to exercise due diligence.
I went to the court serving my district (just Google your district name + "Amtsgericht" to find yours). There were a surprising number of security measures - I had to walk through a body scanner and get my bag searched.
It was actually the first time I've had a less-than-savoury bureaucratic experience in Berlin. It's a worn-down cliché by now that newcomers to the city will complain about the various governmental offices, usually having something to do with the officials only speaking German in... oh, Germany.
I'd never found anyone especially rude in these situations, but when I asked the security guys which way I needed to go, and didn't quite understand as one of them was mumbling, they treated me like I was an idiot. The ladies at the hatch where I then had to cough up my €30 were rolling their eyes and insulting the person who'd just gone before me.
Dude, I've worked with the general public. I know how it is. Vent in private.
I took a ticket and waited for my number to be called. This didn't take long, as it was just me waiting. I went in, said I'd like to leave the evangelisch church (the closest counterpart to the church I was baptised into) and presented my receipt for the €30. I signed a legal document and was instructed to guard it with my life, basically, as all records are destroyed after 10 years, so if I needed to prove any tax stuff in the future and had lost it, I'd be screwed.
Security were very cordial when I left the building, strangely. Smell ya later.
Just to be clear, I had only started receiving the letters from the Kirchenamt since getting a freelance tax number. Yes, I know I hadn't been paying any church tax at my contract jobs, but I wanted to just formally shirk any possible membership and clear things up to avoid problems that might pop up later down the line.