Non-religious stamps now account for approximately 60 per cent - an increased on approximately 40 per cent compared to 2013 - according to the National Federation of SubPostmosters.
The statistics were described as a "disappointing" by one campaign group seeking to promote the presence of Christianity in UK public life.
Tim Dieppe from Christian Concern told the Sunday Telegraph: "It is disappointing. Perhaps secular stamps portray the Christmas story in a more glamourous way.
"There's much in the Christmas story that could be visual. You've got the kinds, the shepherds, the manger, the appearances of the angels."
Sending friends and loved ones a #Christmas card or gift? Why not post them with our special Christmas 2018 stamps?— Royal Mail (@RoyalMail) November 2, 2018
See the collection here - https://t.co/AFHTdVF54Q
-#ChristmasStamps #Christmas2018 pic.twitter.com/GtKFKkdq9J
A new set of Christmas stamps in produced every year by Royal Mail - which alternates every year between issuing new secular and Christian designs.
After including images of famous religious paintings - including the Small Chapter Madonna by Raphael - last year, the postal service published this year twelve designs which are all linked to the iconic British red postbox.
Speaking with Premier in 2016, Francis Goodwin from the Christmas Starts with Christ campaign suggested secular Christmas stamps were a sign Jesus is being "airbrushed" from the festival.
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