I consider deism to be a mistaken belief, as it requires that some form of mind can exist without substance.

An equally mistaken belief might be whether some form of substance can exist without mind, keeping in mind that everything ever known is ONLY known, by definition, because some mind or other is perceiving it.

I personally regard 'self' as pre-existent....but not pre-existing in the form of complex mind. Mind is increasingly complex perceptions of self...it exists as a continuum. Let's face it SOMETHING has to be the basis of reality. One view, your view, places emphasis on 'out there'...it is an 'outside in' philosophy. I don't entirely disagree with it. But another way of seeing things is to literally turn reality 'inside out'. This is my philosophical basis for theism (I regard deism to be a variety of theism).