"That said, it's news to me that Halloween is a Christian holiday, do elaborate(as time allows)."

I didn't say that Halloween was a Christian holiday, I said it has some origins in Christianity.  And in retrospect, it has all origins in Christianity.  The night before "All Saints Day" (Nov 1) It was originally called "All Hallows Eve".  All Saints Day was a feast held to celebrate all the Catholic saints and martyrs, known and unknown.

"Starting at an early age, in the guise of World Studies(or some such), my children were taught many religions in some considerable detail..."

You're saying that your children had a curriculum  whereby they were taught the principals and tenets of other religions, while skipping Christianity?  Or in the course of the obligatory study of the fictitious origins of Thanksgiving they learned a little about Native American culture and did the obligatory "Dress Up Like an Indian" day?

"For my own self, I have no interest in Christmas, for as you say, it has nothing whatsoever to do with Jesus Christ."

Yet you went out of your way to say "You can have Halloween Parties during and after school however Christmas Parties or events are not allowed having been replaced by Winter Pagents or the like."  I don't understand your point I guess.  It's still a party, it's still during the holiday season, but in deference to those who don't observe Christmas, it's not called a Christmas Pary.

"But you're going to have to do more to convince me Christmas isn't being shelved because of it's manufactured connection to Jesus PK"

Christmas is being shelved?  Are Christians being told that they cannot practice their religion or celebrate a religious holiday as they see fit?  Are they being told that they cannot gather in their churches, cathedrals, mega-church auditoriums, or homes and pray, worship, sing, put on plays, or do anything else they want to do?  The worst I can see is that people who don't celebrate Christmas are tired of being told to have a Merry Christmas.  The phrase "Happy Holidays" seems like a pretty decent compromise to me, but that somehow makes Christians think that they're being discriminated against and that their very own holiday (celebrated at the wrong time of year and piggybacking on pagan holidays) is being shut down.  You're buying right into Bill O'Reilly if you believe that one.