My mind's unable to comprehend infinite space, as well as something outside of time, space, or matter. I don't see though how making God an infinitely material object is any more comprehensible than making him an infinitely immaterial object.
I think the correct answer lies from two sources, being science and the Bible.
First, according to the best scientific evidence we have to date (the First Law of Thermodynamics), something materialistic cannot possibly make itself from nothing. Thus, something outside of the material universe must have created the material universe of time, space, and matter we observe and live in. That leaves no room for an infinite material universe and strongly supports an immaterial agent of cause (ie, spirit being or god of some sort).
Second, according to the Bible, God the Father is an immaterial being; God the Holy Spirit an immaterial being; and God the Son a manifested, resurrected combination of the two. In no case does it support a belief in pantheism or any combining of God with his creation. In fact, the Bible specifically addresses the sin of people worshipping the creation instead of the Creator, affirming the distinction between the two.
The first, secular foundation stands on it own, though evolutionists reject the strongest laws of science (and common sense) by adhering to the Big Bang theory. I won't argue with such irrational people. The second, religious foundation warrants its own evidential support, but I'd suggest that I can offer up far more support for it than any religious foundation supporting your preferred theory.
In short, why would you adopt a concept of God that opposes both science and the Bible? You'd have to have an impressive amount of written evidence to rationalize such a view.
