This is using circular logic to try to explain how circular logic isn’t circular logic.
Assuming you don’t screw it up by including a clause which breaks the circle, rendering it false, all circular logic is true. But it’s a vacuous truth: If X, then X. If leprechauns exist, then leprechauns exist. It creates and satisfies its own conditions, but provides no evidence of those conditions occuring in reality. And then you misinterpret exactly what truth has been “proved” and use it as evidence in other arguments, “spiraling outward” as you put it.
It is true that a bedrock foundation of beliefs is necessary in order to form enough understanding to be able to function. *Nobody* starts with the Bible. A baby starts with the evidence of their senses. While it’s very difficult to go through life unaware of at least the dominant local religion without being raised by wolves, not everyone adds it to their bedrock - for a lot of people, it’s superficial stuff, regulated to their peripheral knowledge, and may not even have much effect on their lives even if they call themselves “Christian” or whatever.
The hard part is altering parts of the bedrock once it is firmly set, because you always lose a part of yourself in the process. Depending on the person, it ranges from mildly unpleasant but otherwise easy to completely impossible.
evolution were true, then knowledge would be impossible
Correction: If evolution were true, then your version of God wouldn’t exist. Therefore, if you suddenly truly believed that, huge chunks of your personal knowledge would unravel over weeks or months, erasing most of the person you are now… and creating an opportunity to grow into someone new. For true believers, that’s a fate worse than death.