Well it is a moot point... the universe behaves as though it is material, regardless of teh ontology of the universe. So it may be godthought, dancing energy , butterfly dreams or whatever Mind theory you are proposing.
It is a moot point the universe appears to be material:
One challenge, show any evidence of consciousness absent an organic brain.
So the second challenge, show any evidence that the universe does not behave as though it is material.
Are fields material?
In some ways, the idea of what materialism captures is extended to whatever we can propose to explain the universe around us. Quantum foam anyone?
If I am going to say that "material" means anything I have discovered and anything I ever will discover, the demand to show something immaterial seems a bit disingenuous. As soon as I show it, materialism expands to enclose it as simply a previously unknown part of the package.
Still, as a logical exercise, I am drawn to make some case or other, even though I am a materialist. So, try this:
1) The past does not exist - we can neither observe it nor interact with it directly. It can only be assumed through rational deduction.
2) Cause and effect, a root concept in materialism, demands that the present relies on the past.
3) The present is constructed from non-existent parts and processes.
4) This argument is symmetrical for the future as well.
5) Hence, materialism is grounded in the immaterial.