First of all, that's not what "functional" means.
Second, OO is an orthogonal attribute to functional.
Third, your argument commits a formal fallacy of this form:
All cats have whiskers
Cats can have stripes
Tony has stripes
therefore tony is a cat.
---The possibility of an attribute in X, and Y containing that attribute does not imply that Y is an X.
the point is that whether something is declarative has no bearing on whether it is functional or not. It's an irrelevant point to bring up. Whether something is OO is equally irrelevant. That is what "orthogonal" means. I would go on to define for you "functional" "declarative", "formal fallacy" "logic", but this seems like a bottomless rabbit hole. I can only hope you'll try and find out what these words actually mean yourself.