Popular Christmas carols contain "nonsense", and adults who sing them should be embarrassed, the Bishop of Croydon has said in a book.
The Rt Rev Nick Baines criticised adults singing Away In A Manger "as if it related to reality".
The bishop also suggested that the last word of the title O Come All Ye Faithful be changed to "faithless".
He said Christmas was being sentimentalised into a fairy story, which he said was "tragic".
In a book entitled Why Wish You a Merry Christmas?, the bishop wrote: "I always find it a slightly bizarre sight when I see parents and grandparents at a nativity play singing Away In A Manger as if it actually related to reality.
'Victorian control'
"I can understand the little children being quite taken with the sort of baby of whom it can be said, 'no crying he makes', but how can any adult sing this without embarrassment?"
He added: "If we sing nonsense, is it any surprise that children grow into adults and throw out the tearless baby Jesus with Father Christmas and other fantasy figures?"
The bishop said that a line in the carol Once in Royal David City - "mild, obedient, good as He" - sounded like "Victorian behaviour control".
Explaining his view on O Come All Ye Faithful, the bishop said it was the faithless who came to see the baby Jesus such as shepherds and "pagan" wise men.
He added: "All sorts of fantasies have grown up around Christmas and it has been sentimentalised into the sort of anaemic tameness that has made many people think of it as nothing more than some sort of a fairy story - which is nothing short of tragic, because nothing could be further from the truth."