We are talking here about country and country's culture. What you say works for homogenous societies, but there are plenty of countries with multiple official languages where none of the citizens would be part of their country culture then, look at Switzerland, Belgium, US, etc., these countries don't really have single country culture defined by one common language, but at same time I'm sure all these people living there share similar country culture despite some of them being able to talk to each other.

If you say "any culture" then sure you can be always part of some (sub)culture if you narrow it down, it just matter how much you are going to narrow it, in the end you can be part of culture of foreigners living in specific country.