Definition & Meaning of "the devil is in the [detail]"

What is the origin of the idiom "the devil is in the detail" and when to use it?

The idiom "the devil is in the detail" originated from the longer phrase "God is in the detail," which is often attributed to the German architect Ludwig Mies van der Rohe. Over time, the phrase evolved to its present form, suggesting that hidden difficulties or complications can arise from small or overlooked details. It is used to emphasize the importance of thoroughness and diligence in dealing with the finer aspects of a task or situation.