Answer:
volksgeist
Step-by-step explanation:
Reichstag was a place, not a belief.
Nationalism could be true of any country. It is the belief of in one's country whether that country is right or wrong. It is perhaps the second best answer.
Humanism is characterized by the belief in individual goodness. That is not exactly what the description wants.
The answer is volksgeist which is of a higher nature than just nationalism and it is a more general term. It means the spirit of a country as defined by the spirit of the country.