I once had a very special, very young colleague, who would always question everything, but was never willing to change his own mind. And of course, he believed the Bible was 100% verbatim correct and scientists were lying.

Well, one day he exclaimed, "Scientists don't know everything for certain either!".
So, I responded, "Yeah...? They don't claim to...?".

And that left him absolutely confused. I don't know how much propaganda his parents fed him, but I guess, at the very least he never considered that a possibility.

So, I told him that it's not called a "scientific theory" for nothing. And that literally everything in science will be abolished, if you can disprove it.

After that quick shock, he was already back to not wanting to believe anything that sounded logical, but his last response was something along the lines of "That doesn't make any sense. How can you live by something and not know for certain that it's correct?".

Which, like, I get it. It's scary to not have certain answers. But it makes no sense to just pick one answer and decide that this one is certain.
But yeah, that is the mindset he grew up in.

I wish somebody had told me beforehand that a degree of enthusiastic acting was necessary to spin my miserable results into a success like the superstars in the department, though.

Thats how its supposed to work and in practice it kinda does, but the people with the money want positive results and the people doing the work have to do what they can to stay alive and relevant enough to actually do the work. Which means that while most scientists are willing to change their minds about something once they have sufficient evidence, gathering that evidence can be difficult when no one is willing to pay for it. Hard to change minds when you can't get the evidence to show some preconceived notion was wrong.