For sure: Trump supporters were hiding their approval of him to avoid being scolded by their peers. If you click through that link though, the interviewee mentions actively avoiding pollsters, which is why I mentioned “subverting the efforts of statisticians.” Perhaps I embellished that point a bit, but I think we’d agree that either way the polls were compromised as a result.
As for the God Gap, I would disagree with your implication that it’s being overstated. Three devout Red worshipers for every two Blue ones is a significant difference, and if you focused solely on Christianity those numbers would diverge further.
Ultimately: yes, numbers can’t lie, only people can. I think the simplest way to understand the results is that we should have (and probably did) assumed there was something hidden/silent underneath the polls. The real question was how much, which people clearly underestimated.