And how does one establish the existence of this world-God, and what his "perspective" might be?
Show your work...
Remember. You can't compare abrahamic god to panthenistic god to Hindu god whatever. They all have different characteristics.
I can't speak for Sunstone himself, but if god is everything in the universe, it may refer to this word/term signifying the universe created all (if the concept of god is a creator); if so, you can see creation and creating all over the place. It could be a mystic experience and being a union with all things and people. Think of your euphoria moments, the times you were close to those who you are close to, say spouse, children, friends, so have you. Whatever that closeness feeling and relationship some people call god whether it be the cause or the relationship itself. The physical universe, with us in it, is energy. So, when you tap into energy-whether from people, living things, and for some people objects etc through meditation, prayer, or so have you, they experience god (the whole of the universe).
I'm not sure what you mean by god since I wasn't raised to understand the concept of the abrahamic god beyond RF. But if god is seen as a creator and spirit, then the universe and living do create and we do have spirit or emotions and mystic experiences that we value so much we can't live without it.