One of my PCs (a Cleric of Bahamut) pondered aloud: "Can I use my Insight to determine why my God has brought us here?" There was some entertaining discussion on whether that should be a Religion check instead, but it eventually deteriorated into my players asking for a skill check to be able to read the mind of the DM.

In retrospect, I suppose some kind of ritual appealing for divine guidance would be more appropriate (and effective as well). Regardless, my answer was to laugh at them and then plunge them into an encounter with a metric ass-ton of ice elementals.

My TPKing aside, how do my fellow DMs deal with these kinds of inquiries? Have you ever dealt with these kinds of questions? Do you allow your players to peek behind the screen from time-to-time?