"The rules of "the house owner" that you were mentioning are the laws of the country. What other rules there are to be applied anyhow?"
Well, those parts of one's life that are at the interface or borderline were private life meets interaction with the community that surrounds one. Islamic extremists can live in germany and obey our laws - and still be hostile towards us, look down on us, resist integration and hate germany with all their heart and want to change it into a muslim nation based on the laws of sharia. so, your definition of obeying laws and leave private life to one's private life obviously is to short-longing. It is exactly the kind of understanding a national citizenship as a bureaucratical formality only that I have criticised above. Your hint at not wanting to loose one'S roots is legitimate, and I know what you mean. This I did not demand. One can even offer the hosting people/nation to bring in from one's roots what maybe is compatible with the hosting nation'S rules and ways of living, which then is a benefit and a gift. but the local way of living and rules and values goes first, if it is not compatible, the immigrant'S values have to step back.
So, if you live your pirvate life, what you consider to be that, in a way that you raise hurdles between you and your hosting nation/people, if you live it in such a way that you are perceived by the others as being separate, different - then you do not integrate yourself, but accentuate your status of being different. And this is when i would tell you: you either change your attitude, or you leave.
I would also demand you to have a believable wish to become german, not only because it gives you economical advantages, or legal protections you may not know in the nation you come from - for escaping political violance and help you in a state of emergency, you may request a status of asylum, you must not be accepted by us to be given citizenship and stay forever.
If you do not have a non-material strong interest to live in Germany and live your life according to the "German way of living" and do not have a very strong sympathy and love for German culture and history and identity that is greater than that you had for your old home - then I wonder why you wish to live in Germany...??? If it only would mean for you to leave what you like more, and go to what you like less? I also would ask you what you have to offer us in return that could make it wishable for us to have you with us - a kind smile maybe is not enough, even less so when you still like the value system of your original home more than ours, for example.
It would be of different difficulty for you, depending on where you come from. If you come from central Africa and withoiut a family, then it is diufefrent than if you came from central africa and have seven children with you. Or you come from the Middle East and considers yourself to be a reasonable muslim. If you were coming from northamerica, and yopur ancestors once immigrated from Europe, it would be the most easiest for you, since you would only find different living habits, but no general contradiction in values and cultural traditions. That'S why -beside all my unforgiving criticism of American policies - I will always consider america to be much, much closer to my traditional cultural background than for example that of Bassam Tibi, not to mention a new arriving guy from let's say Afghanistan. Despite all our differences and angry debates, we all nevertheless share the same cultural background in western europe and Northern America - although we sometimes forget that
All in all I see it as your effort and responsebility to integrate yourself - not that of the people in your nation of choice. that people's choice is only if they are goodwilling and give you a fair chance to prove your willingness to integrate, or if they raise as many hurdles as possible to discourage you and get rid of you. But the effort to integrate yourself is your effort, not theirs. Because you want something from them (staying with them in their place, and be perceived as one of them) - they want nothing from you. You need to prove your value for them. If I would immigrate into the US, I would be in the same situation, and would accept it. I better would need to know in advance what enterprise I have started.
I do not talk of Germany only. Replace the term with any nationality you want.