Of all classical works of Halacha, only the Rambam has a section dedicated "Hilchos Deos". For example, he begins with the most fundamental Jewish belief, the belief in one G-d, that G-d is the original existence, that He doesn't have a body, etc.
Yet, none of the other classical Jewish Halachic books (such as the Tur, therefore the Shulchan Aruch, etc.) discuss these concepts at length. These concepts are the fundamentals of Judaism. Someone that doesn't believe in them is a heretic (which has practical ramifications for Yayin Nesech etc.)
Why doesn't the Tur discuss these Halachos?