Sophisticated people, who do not expect to see the Almighty walking around in a long white robe, ask for miracles as proof of God's existence.
If God does not appear in person, at least He should appear in a miracle.
If God wants to prove His existence without showing His face, perhaps He could do something obvious and spectacular.
Philosophically, however—as pointed out many years ago by Maimonides—a miracle does not really prove anything.
A miracle merely proves that something extraordinary happened, and no more.
A miracle that goes against what we call the laws of nature is simply what it is: something astonishing.
It does not have an intrinsic message.
Turning a glass of wine into a flower is remarkable, astonishing, and spectacular, but it does not prove that two times two equals five and a half, nor that God exists.
One thing has nothing to do with the other.
The sea being split or a pillar of fire has nothing to do with anything beyond what they are.
This observation about the invalidity of miracles as proof of God's existence was used at the time when science was far more rigid.
In our time, it is much less effective.
What is the difference between a nineteenth-century scientist and a twentieth-century scientist?
If a devil appeared to a nineteenth-century scientist, he would say, "You do not exist."
The twentieth-century scientist would look at him and say, "You are a phenomenon."
The scientist just writes down that he saw a phenomenon of smaller or bigger magnitude.
However, even this change in the way science views things makes no difference as far as faith is concerned.
Even if people today accept a concept like "miracle" and do not ignore it, or fight against it, this does not necessarily change their worldview.
Namely, they may see a miracle, note it, and then go on with their lives, without its having any effect on other spheres of their lives.
In other words, although science has changed, it has not altered its basic attitude toward miracles.
–Rabbi Adin Steinsaltz
From Simple Words, p. 206, by Rabbi Adin Steinsaltz