For instance; if you accept a scientific suggestion for why something happens to be, there are those who would say, perhaps in good faith, that you believe it to be a fact.

Well I suppose some people might put it that way. I wouldn't automatically assume that they're bringing faith into the equation, though. Perhaps they're just being human and talking more loosely than formally. Without wishing to puts words in anyone's mouth, I suppose they could simply be saying that they have considered the evidence available and, on balance, come to accept the notion.