The issue is that there’s no “register as religion” in Germany in the narrow sense. Religions are registered associations (Eingetragene Vereine) or (Körperschaft des öffentlichen Rechts). You would also register a charity as an registered associations.
If a member of your religion wants to say that you threw him out for unfair reasons, then you can argue to the government that you are a religion and don’t have to provide any rational reasons for throwing people out but otherwise there’s not much difference. In that case a judge would decide whether you should be treated as a religion or shouldn’t.
The issue is that there’s no “register as religion” in Germany in the narrow sense. Religions are registered associations (Eingetragene Vereine) or (Körperschaft des öffentlichen Rechts). You would also register a charity as an registered associations.
If a member of your religion wants to say that you threw him out for unfair reasons, then you can argue to the government that you are a religion and don’t have to provide any rational reasons for throwing people out but otherwise there’s not much difference. In that case a judge would decide whether you should be treated as a religion or shouldn’t.