Ten million of the chocolate gifts are expected to be sold in the run-up to Christmas, with many becoming more and more secular.
Ship of Fools wants to find the ultimate 'Badvent' calendar; the one furthest from the true meaning of Christmas.
It wants members of the public to check the shelves of their local stores to find the calendar 'more likely to please Herod than the Holy Family'.
Francis Goodwin of Christmas Starts with Christ, a campaign that aims to tackle the gradual disappearance of Jesus from Christmas, said: "On window 24 of most Advent calendars you might find pixies, pirates, snow bunnies, even traffic police - but you'll be lucky to see Mary and baby Jesus."
Simon Jenkins, editor of shipoffools.com, said: "It's easy enough to be part of our search. Simply take a picture of the calendar you want to nominate, plus a sentence or two explaining why you've chosen it and send it to us at Ship of Fools."
Nominations will close on Friday 24th October. A public vote featuring the shortlisted calendars will follow with results announced in early November.
The Real Advent Calendar launched in recent years to combat the secular trend.
Telling the Christmas story, it is now stocked in most supermarkets.
Hear Stephen Goddard of shipoffools.com talking about some of the worst entries so far: