In texts aimed at Christians of some denominations, the punning juxtaposition of one’s (presumably godly and wholesome) Sunday life with the harsher “Monday world” appears to be somewhat of a cliché. The book title _Choosing Rest: Cultivating a Sunday Heart in a Monday World_ (link) is certainly a pun rather than an eggcorn. But some of the following examples might not be, or at least might be construed as the the standard metaphor by some of their readers:
* “What does it profit a person to worship God for one hour in a church on Sunday,” laments William Diehl, “but be unable to experience God’s presence in the Monday world?” (Worshipping God in the Everyday Spaces of Life, 2000)
* What are “God’s things?” Are they spiritual rather than material? Are they religious rather than secular? Do they belong to the Sunday world rather than the Monday world? (Spirit of Hope Lutheran Church, October 16, 2005)
* There was a preacher in our town
whose Sunday text was the Prince of Peace,
but
when he looked out at the Monday world– at the uppity
blacks and pushy Jews
and sassy wives and sneaky heathen–blood
scalded his face as purple as if
he’d hung by his heels….
(excerpt from a poem by Philip Appleman, quoted on NJPoets.com)
Rob Leachman comments “Mondays can be rough, so watch out!” And indeed in German, the image of Monday being a particularly difficult day of the work week is reflected in the noun _Montagswagen_, literally “Monday car”. It refers to a car that even though bought brand new, quickly exhibits some defects and faults: a lemon or a dud, in English. The idea behind this is that it must have been built on a Monday, when the workers were supposedly less attentive to detail.