Then you apply the scientific method and/or research in search of truth.

• https://en.wikipedia.org/wiki/Scientific_method

• https://en.wikipedia.org/wiki/Research

What you're asking about there seems like it's really: "Is something being knowledge vs belief subjective or objective?"

The answer, just like for "is cereal soup?", is that it's all semantics. It's not like there's some Authority who's created the Platonic Form of Knowledge that Beliefs cannot partake of, and there's a clear delineation between Knowledge and Belief. We're just using these weird shapes, sounds, hand gestures, or whatever else to try to do telepathy and get our thoughts into someone else's head. Like all semantic questions, what this comes down to is: have you chosen the right word to convey your thought? If people seem to not be getting it, try the other one.

That's a fair question, but we're in danger of conflating two different concepts. Knowledge is the information, and belief is the action. It's a little bit like having money vs spending money. You can have money, you can spend money, and you can have spending money, and you can spend money you don't have. These are all slightly different concepts despite using the same words.

When you think you know something, but you are mistaken, we call that a "belief" even though you did not doubt it. You believe you know something without a doubt, but you are wrong. You do not know, and you should doubt your belief. But you would never describe it as a belief, because you do not believe you do not know for certain.