I've been reading the Catechism of the AJC, and I've learned a lot with just the first couple pages. The hierarchy and doctrinal statements of the AJC have kind of puzzled me in a Gnostic setting, as Gnosticism is not so much about statements but about experience. The emphasis of the curriculum on studying Christian theology also puzzled me.
However, experience without a reference point is meaningless. The Doctrines, as spelled out by the AJC, are there to guide the experiences of the initiates and parishioners. Think of them as signposts. You can go on a journey, but without knowing where you are, having a point of reference, you're not just wandering: you're lost.
Christian Theology has been dealing with these problems for centuries, and so those doctrines and statements also form a valuable signpost from which to proceed. It's kind of like "Ok, I know my friend is over here, but I want to go THIS way..."