From Mark Galli's new book, God Wins, on the nature of asking questions of God (He begins with the contrast between Mary and Zechariah in Luke):

Mary's question is about God. Zechariah's question is about himself.

Mary's question assumes God will do something good and great, and seeks to know how it will unfold. Zechariah is not at all sure that God is good and great, and seeks proof.

Mary wants to learn more about the goodness of God. Zechariah mostly wants to be self-assured.

As I said, there are questions, and then there are questions...

But no matter the questions, here's the point: for some, these questions arise out of a trusting faith. For others, they arise out of a desire to have God prove himself on human terms.

We think pretty highly of ourselves and our questions. We think it's our right to ask such questions and to demand such answers, even from God. But God does not seem to share this view. In the Bible, whenever God is asked a question that throws into doubt his kindness or justice, he more or less refuses to answer. In some instances he says, "You have no idea what you are talking about." Or he says, "You'll get an answer in my good time."

Indeed, there is a deep mystery when it comes to our questions—and yet a deep mercy.