The words on the paper represent the ideas of what it means to be American. Trump has nothing to do with that. His actions, when the do not align with that paper, can be described as "anti-American".
The US has had a total of _one_ government and what it means to be American is in the founding document of that government. To be German is to lay claim to a history and cultural lineage that is filled with many different governments and even different states all-together.
The US has distinct regional and cultural identities as well, to be a Texan means something more akin to being German. Texas has a history that extends beyond the US. One can be American and Texan precisely because they are describe a different thing.
To be American is to ascribe to a certain set of ideals and, as far as someone isn't living up to those ideals, they are "anti-American".
What I read is "what it means to be American" is more clear in ideology and values as "what it means to be German", and I can only wholeheartedly disagree with that.
As someone who is neither born American nor German, I can tell you that both terms describe a subjective feeling and not objective facts. Moreover, they are terms to create unity/solidarity among those who identify with them and exclude those who don't.
Unlike of course someone born Italian telling you that it's clear for everyone what it means to be anti-Italian: ...don't know, doesn't eat pasta or sthg...? /s
Technically, the US has had multiple governments: the original 1781 Articles of Confederation qualifies, as it had a Congress (although a weak one).