Dec. 25th as Christmas has been celebrated since at least the 300s when it appears in the Chronography of 354 and the writings of St. John Chrysostom. According to him, the Roman Christians got the date directly from the census records.
And in support of that idea, the Roman author Hippolytus mentions the birth of Christ on Dec. 25th...he wrote around the year 200.
And anyway, even if it were invented last year, the idea that man *shouldn’t* celebrate the birth of the Savior here on earth is just plain Puritanical idiocy.