Well, first off I have to say, that you cant definde being German by traditions, morality or religion. All those things differ ALOT and its really about where in germany you go.
For example: Try comparing bavarian and nordic german culture. The food, the language, cultural influences etc are VERY different. Further, the cultural roots in the different parts of germany, cant be broken donw to any "german roots". Germany is like 150 years old and is wide mix of different cultures from the very beginning. So if anything, german culture could be defined as a mix of many different cultures. We never had one single set of traditions or values, that you can apply to Germans.
If any person denies being german at all, then his ethnicity is mostly likely far from european. But if we talk about nationality, your pass defines, what nationality you have.
I dont really know where this is going, cause I cant really think of anyone, that has a german pass only and no ehtnic background that isnt european, and that lives in complete denial of being german.
But of course, of someone with a... idk, lets say arab ehtnicity has only a german pass and lives here and hates everything about this country, I dont understand either, what the fuck they are even doing here.
Nice comment overall btw. Im mostly here to show people, what they are wrong about and dismantle their xenophob tendencies.
They see violence, they read "Iran" and then they are already setup to go and bash about the islam and how it was called for that some iranian guy wants to kill germans.
And to this time, I seemed to have been the only that that actually checked for more information and I found out:
"According to information by 'Spiegel TV', the man is suffering from mental problems. His father told them, his son felt persecuted by his neighbours and claimed that they attacked him with harmful beams. Furthermore he was frustrated and angered because of private issues."
All Im trying to do here is making a point. I called people out for being stubborn about that one word (Iranian), instead of waiting, what his actual motives were. There wasnt a single indication, that his nationality, ethnicity or religion has anything to do with all of this and this almost everyone points it out over and over again :)