Might idealist pantheism be true? I'm not sure why it couldn't be. I can't refute it by, say, kicking a stone. Seeming tactile and visual experiences of stones, without physical stones underneath, might all be part of God's plan. It's a bizarre view, perhaps, sharply in conflict with common sense. But something bizarre might well be true. Indeed, I've argued that something bizarre must be true about the basic structure of the cosmos: Common sense is not well-tuned to get it right about such matters, and all of the viable options (e.g., multiverse theory) appear to be highly bizarre.
If idealist pantheism is true, then my mind would have to be part of God's mind. How would that work?
We would have to deny a certain version of the view that consciousness is unified. Assuming that you exist and that I can neither access your thoughts directly nor experience your thoughts as my own, then it must be the case that some parts of God's mind are out of touch with other parts. I see no incoherence in this idea, though, as long as we allow divine mental unity at some higher level of organization.
Divine mental unity might work in part through introspection. God might be able to directly introspect the contents of each individual's mind. On an access view of introspection, this might involve God's having direct access to the contents of each of our minds rather than indirect access (via perception of our bodies). We might imagine a causal process by which each mental state of each individual mind directly produces a judgment, in some part of God's mind to which no individual person has access, that that person is in that mental state. One way this might be realized would be through a divine version of Global Workspace Theory: Each person might be like a separate processing module in the cosmic mind, whose contents are fed into a divine cognitive processing system that integrates the inputs.
But in order for this to be introspection rather than perception, these inputs into the divine mental workspace would have to be inputs from pieces of God's mind rather than inputs from things external to God's mind. And that means that God would have to think with and through us, instead of merely about us. And this probably requires some kind of divine limitation or restraint or trust. If every one of my thoughts is independently assessed by God and handled suspiciously -- if those thoughts do not, in some sense, normally speak for God or for some part of God, if those thoughts are normally held at a distance for evaluation as though not God's own, then I think what we would have is not pantheism but rather the more ordinary view that I am one thing and God is another thing who judges me.
What I am imagining, then, is a rather unusual conjunction of views: vast divine knowledge of the contents of our minds combined with a lack of divine mental independence. God would have to have lots of knowledge but not a lot of processing power in the central workspace -- whatever processing power God has would have to be to a substantial extent actually distributed among us. If so, then presumably our collective judgment would have to in some manner constitute the divine judgment and probably too our collective action would have to in some manner constitute divine action. Otherwise we would not be part of God's mind but something outside of God.
Let me admit that the likelihood of all this being true seems to me rather small -- though since it seems at least possible and since I mistrust common sense in matters cosmological, I'm not sure what justifies my inclination against it.