Plus the whole "necessarily existing and containing all properties" thing is a stretch imo.
I think this is a lot more obvious if you go through his reasoning.
Personally, I think it comes down to consciousness/subjectivity/experience. Is there an overarching "creative" consciousness? Obviously the bearded-man-in-the-sky model is childish, but if you think about consciousness objectively enough for long enough, I believe one of two basic explanations becomes necessary:
-
Consciousness is an emergent property of a sufficiently complex system, e.g. the human nervous system
-
Consciousness is some field/force/property of nature that conscious beings tap into in some way
No other explanation really holds up to serious scrutiny (though if you have a reasonable alternative, I'd love to hear it).
If 1, it stands to reason that entities larger and more complex than humans should develop consciousness of their own cosmic variety: stars, galaxies, galactic clusters, the totality of the energy composing the universe(i.e. God). It's silly to assume that humans are the precise complexity level which develops consciousness, and nothing higher or lower has any comparable phenomenon.
If 2, that field is functionally indistinguishable from God.
I think the above mentioned bearded-man-in-the-sky, Sunday school conception of God as a glowing hand with a booming voice that descends from the sky muddles things. It's a severe oversimplification and any thinking person is right to reject it, I know I did. Strip away the cartoonish characterizations and the literal interpretation of fantastical scenes from the Bible, and consider the fundamental properties ascribed to the concept. Seriously ponder the nature of consciousness, does any explanation make sense other than the Universe = Energy = Consciousness; omnipresent, omnipotent, omniscient?