How do we know that God didn't wind up the Cosmos and simply walk away, as Deism professes?

Fourteen reasons come immediately to mind.

First, there's no evidence such a thing happened, and a great deal of evidence to contradict this presumption.

Second, it's odd in the extreme to think God would make an anthropic universe designed specifically for us only to simultaneously be apathetic about us. If He were apathetic towards us, why did He bother with the tiniest details on the subatomic level and make them consistent throughout space and time?

Third, the universe has purpose and order. The Anthropic Principle clearly shows the Creator had foresight and omniscience (i.e., knowledge extending beyond space and time) thus He couldn't have forgotten about us or the Cosmos in general.

Fourth, the anthropic nature of our Cosmos belies the Creator's love and perfection. Why make the universe so perfectly fine-tuned for us and then give up caring? A perfect and loving God simply wouldn't walk away abandoning us to our own devices as if not caring if we were good and kind to each other. In other words, if God walked away from us, it would mean He was apathetic. If He were apathetic, then He wouldn't be loving. If He weren’t loving, then why make our Cosmos so perfectly anthropic?

Fifth, the existence of inspiration is a thorn in the atheist's side. As we indubitably live in a deterministic universe, how can we account for the presence of inspiration (i.e., something that is new and not the cause of anything prior to it)? If something causes something else in turn, whence comes inspiration? Since inspiration falls outside of all known laws of the Cosmos, we are left only with God as its Author. Thus, being the case, He's obviously at the ready, waiting for us to call upon Him.

Sixth, the basic nature of the Cosmos is one of entropy—a thermodynamic quantity representing the amount of energy in a system that is no longer available for doing mechanical work. That is, everything breaks down. However, the exact opposite is happening to our universe as it expands. In fact, it's moving faster and faster. This is impossible considering the immutable nature of the laws of the universe. As the expansion of the Cosmos isn't isentropic (i.e., with unchanging entropy; at constant entropy), this suggests God is attentive to us and not at all apathetic otherwise the natural laws that He laid down at the Big Bang would hold true even for Cosmos' expansion. It could be argued that the rapidly increasing nature of the Cosmos' expansion is part of God's wind-up-and-let-her-go strategy but this is stretching. The more care you put into a system, the less apathetic one is. The fact that things are so perfectly balanced in our universe and, seemingly contrary, to the established rules of the universe, the less likely one can say God is apathetic to us and to it in general.

Seventh, free will exists. If God had intended the Cosmos to work like a wound-up clock, it's odd He would have bothered with free will at all. Free will only mucks things up in a system that you don't want to be bothered with.

Eighth, the existence of morality not being caused by culture or dependent upon evolution is strong evidence that God isn't apathetic. If He truly didn't care about us and our spiritual development, why bother placing the laws of morality in us in the first place? It's odd in the extreme to think that a Deity didn't want us to be apathetic toward each other was, in turn, apathetic towards us.

Ninth, though the anthropic nature of the Cosmos clearly shows it was made for us, it was done only to honor the Creator's own majesty and glory. This is why we congratulate artists for their work and not laud the painting itself. It's odd to think we would ignore the Creator of the Universe and still credit Him for His work.

Tenth, as of the date of this book's publication, astronomers have discovered approximately 7000 planets, none of which harbor life as we know it. Why would God make us, the only known intelligent life in the Cosmos, only to walk away ignoring us? Had He stopped with worms or dinosaurs, that might make more sense—but not with a species that was sufficiently introspective and curious to wonder about its own mortality and origins.

Eleventh, apathy is a human quality which is the result of sinfulness, narcissism, greed and a lack of compassion. A loving Creator couldn't, by His own nature, be apathetic about anything or anyone.

Twelfth, the anthropic nature of the universe suggests perfection in our Creator. For atheists to suggest that God had somehow “become” complacently apathetic suggests a fundamental change in God's outlook. A perfect Being couldn't change. Further, change is the result of causation, which isn't a part of God's makeup as He isn't a part of our physical Cosmos. If He were, then how did He manage the Big Bang?

Thirteenth, there is no "walking away" from us as there is nowhere to be had outside of the universe. There's neither space nor time outside of our realm by the very fact that scientists agree that spacetime was created at the Big Bang and not prior to it. God is both eternal and infinite because there is neither space nor time outside of the Cosmos. He is there because He never left.

Fourteenth, suggesting God is apathetic is a pagan notion in which adherents ascribe human qualities to their imperfect false gods. God's perfect nature presupposes perfect love.

The nature of God is shown in the anthropic nature of the universe. Deism is merely the unproven, wishful thinking of atheists―it's simply yet another form of atheism, which itself is a form of paganism, that conveniently explains why things are as they are (i.e., the anthropic nature of the universe) while still excusing the adherent's personal moral turpitude, perfidy, selfishness and apathy (not God's). It's the most current permutation of the atheist "non serviam" first uttered by Lucifer at his fall.