Perhaps you've heard the proverb "Idle hands are the devil's playground." I have also heard that it's within an idle mind, and not hands, that El Diablo finds his jungle gym. Another variation is "The Devil finds work for idle hands to do." In Bartleby's, the closest thing I found to an official quote was in a verse by Isaac Watts (1674 - 1748). The relevent lines follow:

For Satan finds some mischief still
For idle hands to do.

Isaac Watts, Divine Songs. Song xx.

It's not hard to divine the meaning of this proverb. To me it is related to the Protestant Work Ethic. Not that you can work your way into heaven, for John Calvin clearly did not believe that. He believed in predestination. You were either chosen or condemned, and no amount of faith or work, or sin for that matter, could reverse it. But if one dedicated oneself to an ascetic life of tireless service and good works, wouldn't it be obvious that you were one of the chosen? It is rather common these days to misinterpret the Protestant Work Ethic as working oneself to death to get into heaven. Or, alternately, if you keep busy, you won't have time to sin. However the term is used or interpreted, the result is the same, all work and no play makes novasoy a good Christian. So I had better get back to work and stop noding!