Where have all the Miracles Gone?

As a kid, I often left Sunday school wondering why God was so much less communicative today than he had been in Biblical times. Back then, according to the stories I heard, he was constantly speaking, out loud apparently, to some patriarch or prophet. Further, the Holy Book was chock full of flashy, often public miracles that made God’s presence and intentions abundantly clear to even the most hardheaded skeptic. Pharaoh, it appeared, even if he were even stupider than the usual royal dolt, would surely have recognized by the sixth or seventh plague that he was up against a dangerous supernatural being. Elijah vs. the priests of Baal (I Kings, chapter 18) was even a fine example of a crucial experiment. Surely nobody who had witnessed that could have the least bit of doubt that Baal was a fake and The Lord was the genuine article.
Yet, in our day, when there were as many bad guys and as much doubt and uncertainty as in the old days, God was strangely quiescent. No voices boomed from on high, no seas parted, and everyone dead stayed that way. When I asked, I was told that the age of miracles was over and that God expected us to believe on the basis of faith rather than spectacular demonstrations. Whatever the reason, it seemed abundantly clear that big, obvious displays revealing God’s purpose and power simply did not occur. Hitler could oppress the Jews far worse than Pharaoh, but his destruction came not from supernatural plagues, but from entirely earthly causes–Allied guns, tanks, and bombs.
No doubt some would claim that miracles do in fact still occur. For instance, on very rare occasions patients with advanced metastatic cancer will spontaneously and mysteriously recover. Their tumors will just go away for no apparent reason. But such cases surely are more reasonably interpreted as having unknown natural causes that medical science would very much like to discover. In fact, once you have weeded out the reports of quacks, cranks, charlatans, and special pleaders, there just do not seem to be any robustly verifiable miracles left. There is nothing at all like feeding thousands with one Happy Meal or public displays of aquatic pedestrianism. If they do occur, why are TV cameras never present?
Some might say that miracles, in the sense of physical effects brought about by the intervention of supernatural entities, occur all the time. For substance dualists, everything we do has a supernatural cause—the soul. For dualists, it is literally a miracle that I am now moving my fingers to write these words. Such events involve the intervention by a supernatural entity into the physical world. However, such a claim is highly tendentious and would really only serve to redirect attention to a critical discussion of substance dualism.
It therefore seems that we could conclude that, by far, the best explanation for the absolute absence of verifiable miracles is that they are not happening, and, further, that the reason that they are not happening is that there is nobody there to perform them. Such an inference would prima facie seem far more plausible than alternative explanations, such as that miracles occur but that today’s unbelievers refuse to admit it or that, for some reason, God now hides his miraculous interventions. If you keep not getting valentines from a secret admirer, the best explanation of this sad state is that you have no secret admirer.
This “no miracles” argument is, of course, an aspect of the general problem of divine “hiddenness.” However, I think that it has advantages over a more general statement of that problem. A standard reply to the hiddenness argument is that if God made his presence too obvious, belief would no longer be a matter of free choice. When something is dead obvious, the belief is forced upon us. We would obey God out of prudence rather than due to a freely-given loving response to his grace. But such a reply is difficult to square with the fact that, according to holy writ, God did make his presence and power very obvious to large numbers of people with very public miracles. Many of Jesus’s miracles were performed in public. Famously, (I Corinthians 15) the risen Christ supposedly appeared before 500 of the “brethren” at one time. In the OT, the miracles are often truly Spielbergian displays performed before gaping multitudes.
The salient question then is why in those days it was appropriate for God to leave no doubt about his existence and will but not now. Did God change his mind? Why would a free, uncompelled response to God be so important now but not then? What answer would not be arbitrary or ad hoc? If a free, faithful response is so important now, why was it not back then? On the other hand, would not some big, public miracles be  a great benefit today? When, by the way, did the Age of Miracles end? There are many lively reports of miracles in the literature of the Middle Ages. Indeed, it appears that respectable sources report miracles often right up to the Enlightenment when miracle reports went out of fashion with professional historians. Did God keep performing public miracles right up to the time that educated people started getting skeptical about them? Wouldn’t that have been the time to perform more and more public miracles to counter the corrosive effects of skepticism? Why not some parting seas or resurrections to instruct our notoriously unbelieving age?