I don't think Christians who for selfish reasons hijacked Saturnalia centuries after the death of the alleged Jesus Christ have any monopoly on December holidays by any stretch of the imagination, only a truly clueless person would believe that
And I don't understand why a non-Christian in particular would ever get upset by "for the holidays" or cheer for the Christian's completely manufactured culture war based on something they don't even own — their own Bible indicates that the alleged Jesus Christ was not even born in December:
https://www.ucg.org/the-good-news/biblical-evidence-shows-jesus-christ-wasnt-born-on-dec-25
"Happy Holidays" is no more made up out of thin air than is "Merry Christmas"
It's not about tolerance or inclusivity, it's about hard, cold reality versus being full of sh*t