As mentioned in the post, a lot of Greek philosophers and a lot of others since them have been panentheists (which probably am as well). In this view God is both transcendent and outside of the world, but also immanent, inside it. Whether the world is world/God or world+God is open. My own view, largely coming from the dual aspect monism thinking, equates Spirit with the One--the unus mundus. Since panentheistic views involve God directly in the world and it is a God who acts then praying to the God of the Philosophers makes perfect sense. Especially if God is seen as Good and/or Love as with Plato and St. John.