Why is Christmas portrayed as Santa Claus if we celebrate it due to the birth of Jesus Christ? And why is Easter portrayed as a bunny if we celebrate it due to the resurrection of Jesus Christ?
Christmas is not "portrayed as" Santa Claus. Neither is Easter "portrayed as" a bunny. This is not a Christian phenomenon - far from it!
It is American post-Christian, un-churched, and non-Christian pop-culture and media that over-emphasized Santa Claus and the Easter Bunny because both were religiously safe in that both could be easily secularized and universalized whereas Christ's birth could not be. But blame Madison Avenue and Hollywood ... and the unseen consequences of the Framers' 18th Century quaint if naive notions regarding religion and religious liberty. (They never imagined America would be anything other than 99% Protestant and/or Unitarian.)
At any rate, note the cultural appropriation and exactly where they cut the actual lyrics:
For the unchurched, the 2nd bar of Joy to the World is THE LORD IS COME! -- not, Narf, narf, narf! And the 2nd bar to Hark the herald angels sing is GLORY TO THE NEWBORN KING!
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