To me from the definition, it seems that anything you know must be counted as beliefs. To me belief just means saying that X is true. If you know that X is true for certain, then your belief is a correct belief. For example, I know the sun exists because I can see it and sciences have proven it exists. Therefore, my belief in the sun is correct. Now, we cannot know if there is or isn't a god. Therefor someone may belief that god exists, but we cannot prove the belief is correct or not. It stays as an unprovable belief.

However you are fully right, it's just semantics. You're going by a definition of belief as "something we think is true but can't prove", where I'm just using "something we think is true".

However, I still will say that you think the sun exists. If you wanted to argue that you don't think the sun exists, you would have to prove to me that you think that the sun doesn't exist, or that you don't think about it at all. The fact that you're talking about the sun and saying you know it exists, implies you're giving this some thought. In order to have typed out any of your comment, you had to have had the thought in your head, then let your fingers translate that thought into text. So you do think that the sun exists.

In turn, religious people think that god exists, they belief god exists, and they also think/belief that they know god exists.