I’m no Spinoza expert so I don’t want to say whether he got it right or not. I’ll let you draw from what I say what my opinion might be on the matter.
I think I hear what you’re saying though about a separation between physical and spiritual and this tendency toward “us and them” thinking. (If such a separation was the case, what could we ever say about God or spirit? Whatever we did say would be tantamount to a lie, or at least a stab in the dark. And feuding would result if we took ourselves too seriously.)
Maybe I could put it this way then: While I would separate the physical from the spiritual I would also suggest that their union is precisely what we call life. You know, God breathing into the dust and the result being Adam?
The two remain separate, or separable, but nevertheless unified or unifiable as a lifeform. I would further suggest that this union established at our conception gives us access to both the physical and spiritual domains in our lives, which is to say the ability to speak of/for God without it being a stab in the dark.
To clarify though, I would say that speaking of/for God is a second order “channeling” of the spirit. The union of dust and spirit at conception is the first order, or what I called before our being in God. Our communion with God’s will/word/nature in our lives is the second order, or what I called God being in us.