Devil in the detail / Teufel im Detail

The source of the proverb 'The devil is in the detail' is often (mis)attributed to the German architect Ludwig Mies van der Rohe, though both Nietzsche and Flaubert seem to have used it earlier.

In fact, it may derive from an older German saying "Der liebe Gott steckt in detail" ('God is in the detail'). I can’t find any explanation of why it switched from god to the devil.

Neither am I sure why this round hole in my daughter’s school playground casts such a devilish shadow!