The majority at least? Where I live, people say we have a church on every corner. Because we almost literally do. I drive past 5 just on my way to work every day. They wouldn't be there if people didn't attend. In my experience, even most of the non-affiliated will say they believe in a "higher power" or somesuch. In the Pew survey, only 6% out of the 29% non-affiliated identified as agnostic, and only 5% as atheist. Living in the south, having grown up in the bible belt, I can say with very high confidence that more than 5% of Christians actually believe in god. I'm sure some do maintain a facade for social reasons (I did myself for a few years, though would have been honest on an anonymous survey), but certainly not 95%+.

I'm sure it varies by location (obviously, the bible belt was thusly nicknamed for a reason), but the idea that less than 5% of Christians anywhere actually practice / believe in god just stretches credulity.

Where is “Pew” to save this one?

Right here: https://www.pewresearch.org/religion/2025/02/26/religious-attendance-and-congregational-involvement/