People living in $M$ cannot construct a $G$ which is $P$-generic over $M$. They may believe on faith that there exists a being to whom their universe, $M$, is countable. Such a being will have a generic $G$ and an $f_G=\cup G$. The people in $M$ do not know what $G$ and $f_G$ are but they have names for them, $\Gamma$ and $\Phi$. They may also read the preceding few paragraphs and thus figure out certain properties of $G$ and $f_G$…

I could only say that Paul Cohen’s idea on the Continuum Hypothesis is amazing. And I am quite curious about his religious belief.