in order to serve as president or in congress.
If you take an oath to operate as the constitution requires, and to defend it, you should have an understanding of what it says.
This president clearly does not even begin to understand the basics. Or if he does, he ignores them. In these circumstances, what is the point of an oath? An oath assumes knowledge of the oath's subject-matter.
If a person does not know this much, how can they serve in conformity with the constitution?