1. It is none of the governments business whether someone is a member of a church or not.
2. Church has no business being intertwined with Caesar.
Germany used to be a vast, decentralized network of territories, city-states, principalities, all of them more or less local and autonomous, each with its own self-governing codes and customs. Many bishoprics, abbeys and convents throughout Germany were granted temporal estates just to provide order and continuity. This in itself (lay investiture) was a major crisis in the feudal period, as popes opposed the appointment of bishops by princes.
The reform-minded popes (e.g. Gregory) tried to block emperors using the bishops this way. Then in the Reformation, abbeys, convents, and diocesan territories were largely handed over to Protestant princes. Finally in 1803 a great deal more was seized and transferred to new secular rulers.
Then in the 1870's, the Kulturkampf culminated in Bismarck tring to seize just about all things Catholic: schools, hospitals, publishing houses, the imposition of civil marriage, the jailing of priests and bishops, etc.
Bismarck finally gave way when he faced a bigger political crisis than he had bargained for. The new settlement resulted in churches (Evangelical and Catholic) giving up income (from properties) and accepting compensation, VOLUNTARY, collected from identified CHURCH MEMBERS.
That's bad?
But you would like to get rid of the tax. I'd agree. You also want to restore all the expropriated Church properties this was supposed to be compensation for?
Or do you think the Church should be required to bestow Sacraments on declared non-members?