Update I haven’t any idea how I did it, but I somehow turned off comments on this post. They are now restored.
The conception of what God is went downhill after Aquinas. And, dear atheist reader, shouldn’t you know what it is you claim to reject? New Atheists in particular have been shockingly Would it surprise you to learn that the Church rejects the same gods, or same weakened conception of God, you reject? This chapter, which is broken over multiple posts, shows that God is not a physical body, that God is not a creature.
Chapter 20: That God is not a body
1 FROM the foregoing we are also able to prove that God is not a body.
2 For since every body is a continuous substance, it is composite and has parts. Now God is not composite, as we have shown. Therefore He is not a body.
3 Further. Every quantitative substance is somehow in potentiality: for that which is continuous is potentially divisible to infinity; and number can be infinitely augmented.i Now every body is a quantitative substance. Therefore every body is in potentiality. But God is not in potentiality, but is pure act, as shown above.ii Therefore God is not a body.
4 Again. If God were a body, He would needs be a physical body, for a mathematical body does not exist by itself, as the Philosopher proves, since dimensions are accidents.iii Now He is not a physical body; for He is immovable, as we have proved, and every physical body is movable. Therefore God is not a body.
5 Moreover. Every body is finite, which is proved in regard both to spherical and to rectilinear bodies in 1 Coeli et Mundi. Now we are able by our intellect and imagination to soar above any finite body. Wherefore, if God were a body, our intellect and imagination would be able to think of something greater than God: and thus God would not exceed our intellect: which is inadmissible. Therefore He is not a body.iv
6 Furthermore. Intellective knowledge is more certain than sensitive. Now among natural things we find some that are objects of sense: therefore there are also some that are objects of intellect. But the order of powers is according to the order of objects, in the same way as their distinction. Therefore above all sensible objects there is an intelligible object existing in natural things. But every body that exists among things is sensible. Therefore above all bodies it is possible to find something more excellent. Wherefore if God were a body, He would not be the first and supreme being.v
7 Again. A living thing is more excellent than any body devoid of life. Now the life of a living body is more excellent than that body, since thereby it excels all other bodies. Therefore that which is excelled by nothing, is not a body. But such is God. Therefore He is not a body.vi
8 Moreover. We find the philosophers proving the same conclusion by arguments based on the eternity of movement, as follows. In all everlasting movement the first mover must needs not be moved, neither per se nor accidentally, as we have proved above. Now the body of the heavens is moved in a circle with an everlasting movement. Therefore its first mover is not moved, neither per se nor accidentally. Now no body causes local movement unless itself be moved, because moved and mover must be simultaneous; and thus the body that causes movement must be itself moved, in order to be simultaneous with the body that is moved. Moreover no power in a body causes movement except it be moved accidentally; since, when the body is moved, the power of that body is moved accidentally. Therefore the first mover of the heavens is neither a body nor a power residing in a body. Now that to which the movement of the heavens is ultimately reduced as to the first immovable mover, is God. Therefore God is not a body.vii
iWho knew St Thomas was familiar with analysis! (The first argument above I left uncommented, it being obviously sound.)
iiDon’t forget to review what these terms mean, particularly act and potential. Don’t assume you know how St Thomas and Aristotle meant them.
iiiFrom The Philosopher, lovely as always (yes, but was this peer-reviewed?):
A question connected with these is whether numbers and bodies and planes and points are substances of a kind, or not. If they are not, it baffles us to say what being is and what the substances of things are. For modifications and movements and relations and dispositions and ratios do not seem to indicate the substance of anything; for all are predicated of a subject, and none is a ‘this’…
But if this is admitted, that lines and points are substance more than bodies, but we do not see to what sort of bodies these could belong (for they cannot be in perceptible bodies), there can be no substance. Further, these are all evidently divisions of body, one in breadth, another in depth, another in length…
iv(Heaven and Earth.) St Anselm, anyone? Don’t let’s forget that Contra Gentiles came before Summa Theologica in Aquina’s thinking. See 2c here.
vAs a sound argument, this bullet is shaky, assuming what it seeks to prove, it seems to me, at the end, in much the same way as the ontological argument fails. But, the first premise is certainly true: “Intellective knowledge is more certain than sensitive.” One can mistake cold for hot, but not that you know. This is why many also say mathematical knowledge is supreme.
viThis one is too telegraphic, maybe. We have “Therefore that which is excelled by nothing, is not a body”, which we can grant. But angels are not bodies, and we haven’t yet shown that these are lesser than God. Certainly, this argument is weak. But. If, as he does, St Thomas offers two dozen arguments for a proposition, and one or two fail, this does not imply the others fail, which (as shown) they do not. Do not be intellectually lazy and ponder only that which is admitted to fail. And anyway, like the ontological argument, much can be learned from the failures of these arguments.
viiIf you key in on the heavens moving circularly bit, you’ll be missing the point. This argument, which does not for a mote rely on that contention, is really no different than the proof of God’s existence because in order for anything to move—here and now—we need a first unmoved mover. Go back and read Chapter 13, as St Thomas himself commands in the footnotes. Ch. xviii.
 Ch. xvi.
 2 Metaph. v. [This is a typo; it should be 3 Metaph. v.]  Ch. xiii.
 Ch. v. seqq.
 7 and 8 Phys. See above, ch. xiii.
 Ch. xiii.  7 and 8 Phys. See above, ch. xiii.