A Question of Faith

After my previous post about taxes this is a more specialised concern. More of a question really. Something that has been on my mind.
I've described the tax situation. I've mentioned the "church tax". In Germany, the Church (both Protestant and Catholic) may levy taxes at the rate of 9% of your income tax. That then gets added on top of everything else. Individually it may not be much but things add up. The revenue from this tax makes about 70% of the Church funds.
Now, there is a way to eliminate it, as I've hinted at: you can leave the church and officially become what is called "undenominational", meaning before the law and the Church you have no religion. With that you also loose the right to claim the services of a priest.
To save some tax I've chosen that route. I've already taken the first step by going to the magistrate's court and declaring I wish to leave the Church. Formalities will now go their usual course. That's roughly when the questions started plaguing me. I've written before that I've started to believe in God. I want to. I believe that even this little faith has done some good things for me. A prayer just before my job interviews, for example, seemed to make them go more smoothly - and more successfully. I've always tried to remember to say thanks but now by leaving the Church I feel a bit like a St. Peter. I feel uncomfortable, remorseful. Am I not betraying Him just as He has begun showing me His kindness? It seemed like a small thing before. Then when the officer said I would become "undenominational" it felt as if she had said "faithless". Isn't this denial? In refusing to pay this tax to support the Church am I denying God? Or asked the other way round: If I recognise God am I also required to provide for His declared servants on earth? I comfort myself with the idea that if I require a priest I will make a donation directly to that person. But that's only part of the solution. All sorts of official documents will now have this word on them. This word that says to the world that I believe nothing. Of course, what's really important is what's in my heart (probably a lot of people list a denomination but don't believe at all). I don't need to go to church to have God in my heart. Still, will He think I'm petty or greedy that I value those 9% so highly? Or will He forgive me because on His earth everyone has to make a living as best they can? Jesus did forgive Peter his denials. Then again, Peter was his disciple and had shown his faith many times before. A year ago I would never have thought that this would end up being a question of faith. And I don't believe there is an easy answer to it either.