As mentioned in the previous post, the Rishonim ask how there can be a mitzvah to believe in G--d when the assumption that G-d exists and can command us presupposes accepting the mitzvah itself. For this very reason, writes R' Tzadok haKohen (Tzikdas haTzadik #207), the first dibra of "Anochi" reads as a statement of fact. The Torah is informing us, not commanding, that belief in G-d is part of our essence, something which is natural to every human, and that trait of belief is lost only due to our corruption of a healthy mindset. With this we can understand the striking statement of the Rambam that when we see [deliberate] kofrim we can assume that their souls were not present at Sinai and they are not truly of the stock of the Jewish nation. Everyone who is Jewish inherently is a believer.
Clearly there are degrees and levels of belief, but there seems to be some confusion as to what is meant by levels of belief. There is no shiur for the mitzvah of emunah -- it is not enough to say I am 51% certain that G-d exists, and "rubo k'kulo" so I am yotzei the mitzvah. The use of the word "da'as" by the Rambam is a giveaway that we are dealing with knowledge, which implies (or may even mean) belief that is certain and true, not just probable. R' Elchanan writes (Agados al Derech haPeshat end of Yevamos 12:10-11) that emunah must exceed even the level of certainty we have that what we see with our eyes is true! The eyes can be deceived, but emunah represents an acknowledgements of unquestionable truths.
So what do we mean by levels of faith? A mashal: I like music and can appreciate that Mozart is a brilliant composer. But I am just an amateur without even a good ear. Someone who studies at Juliard School for Music may say just as I do that they like Mozart, but their appreciation of Mozart is vastly superior to mine. Does that mean that my appreication is false or that I am less certain of my apprectiation? Of course not! Emunah is like appreciating a symphony or great work of art. There are multiple levels of appreciation each of which is true.
There is an espitimological difference between what we know to be true based on what our minds tell us and what we accept on faith alone, but that difference has no bearing on our certainty in both types of beliefs. The acceptance of the unseen as being as real as that which is before our eyes is the yichud of emes and emunah.