That depends on what you mean by being a “part” of something. The handle of a paint brush is not ontologically identical to the brush. Of course if God is an intrinsic expression of a things essence, then that would be a problem since in that case a things “whatness” would be God. Since we know that at no point does act become identical with essence, even when conjoined, then we know that God does not become the “whatness” of thing by conjoining his power of actuality with an essence. Esse (the act of reality) never becomes identical with creatures. The act of a creature is not identical to the creature and this is made evident by the fact that creatures come in and out of existence.
The handle of a paint brush is not identical to the brush, but neither are the bristles. The brush is the sum composite of bristles and handle. Likewise, a creature is not identical to its esse but neither is it identical to its essence. If that were so, all men would be exactly the same. All trees would be exactly the same. Things of a certain species are alike in their essence, but different precisely
in their existence.
We can take the logic further and say that if creatures were identical to their essence, not only would they be identical to one another, but their existence would have to be included in their essence.
Not only is God the only thing identical to His existence, He is also the only thing identical to His essence.
But the point is this: by your theory, whether or not God became the “whatness” of a creature, He would become the “isness” of the creature, which would obviously mean that the creature
is God, albeit under the appearance of some particular form of “whatness.”
You are speaking about a different kind activity and dependency here that has nothing to do with having the power to bring potency to act.
There is no such thing as an activity that has nothing to do with “the power to bring potency to act.” That is exactly what “activity” is:
activating, or
actualizing, a potency. The source of your error is apparent in your reply to Aloysium, which I shall address shortly.
That a brain processes data is secondary to that which brings the potency of these processes to act. That which is essentially distinct from actuality cannot be that which actualises potency.
A creature is not distinct from its actuality, otherwise it would not be a real thing. It is distinct from the act whereby it is made an actuality.
Creatures are mediums of God’s power, they do not have their own distinct source of power.
On the contrary, “God created man a rational being, conferring on him the dignity of a person who can initiate and control his own actions.” (CCC, 1731). And more to the point, “Freedom is the
power, rooted in reason and will, to act or not to act.” (CCC, 1732)
If creatures (specifically rational creatures) did not have their own distinct acts, and therefore their own power, that would mean that either a) God did everything for them or b) creatures could manipulate God’s power, which is His will, to their own ends.
Creatures have their own power, but that power is given and sustained by God.
Moreover, “that whereby an agent acts is its act.” A thing acts
according to its nature, but it does not act
by its nature. It acts by its existence: only an act can move potency to act. But God’s act is
His act alone; it is His will. It cannot contradict itself. Free will would be impossible if we did not have our own
act.