God's Name is absent in the Megillah that records the story of Purim, and God's power seems to be absent, too.
We refer to Purim as miraculous, but where are the miracles?
On the surface, everything seems to be explained.
Everything is rational, with a clear cause-and-effect chain.
So where is the miracle?
To understand it, we have to know that there are, generally, two kinds of miracles.
In the miracles of the first period of Jewish history, the ones that we celebrate on our major holidays — Pesach, Shavuot, Succot — Divine providence was obvious.
When the Red Sea was divided, the face of God was apparent.
In the events on Mount Sinai, the face of God was apparent.
These and other supernatural miracles — miracles of the first order — are clear, and they are visibly directional and intentional.
But in the post-Biblical world, clarity and direction are often lost.
Purim happens during this very different time in our history.
When we say that God is "hiding His face" in the Purim story, it is not just a play on words; it is a basic notion.
Part of the miracle of Purim is that everyone is masquerading, acting drunk, and thinking that they are doing things for their own benefit, but it is because God is acting "off stage" that it comes together for a good ending.
–Rabbi Adin Steinsaltz
From as essay, "Purim: Life is a Masquerade" by Rabbi Adin Steinsaltz