If God exists, which Descartes believes can be demonstrated philosophically in the form of the ontological argument, then this Good must be a just. A just God ensures that the external world, which he created, corresponds to my inner world. Thus I can be sure that my idea of the cup, which I am entirely certain of, is the same as the actual cup which exists in the external world. What Kant calls a dogmatic slumber is this heady mix of theology and philosophy. The fact that theology has sneaked into philosophy tells us something has gone wrong.
Theology is usually philosophy gone a bit mad.
This can make theology interesting, but also a little suspect in its own commitment to argument. Thus what we need to do is go back to the relation of knowledge itself, and see what really appears there without introducing a deus ex machina, or other metaphysical hobgoblins. First of all there is subject and there is an object that confronts this subject. We supposed to be learning what transcendental idealism means, and yet we are told he explains the world immanently. We need to make a clear distinction between transcendence and transcendental in Kant s philosophy.