"The Jehovah’s Witnesses have banned all mention of Christmas, calling it a pagan holiday. Even some Seventh-day Adventists have fallen into this trap...."
Tom, I enjoy Xmas time, but I do recall debates in the church where some said it should not be recognised, due to its pagan origins.  The quotes you have from EGW were not mentioned, that I remember.  

But it doesn't take too much research to recognise that the northern midwinter festivals, eg Saturnalia, preceded Christmas by many centuries.  And the Puritans of the C16 were not the first to reject Christmas celebrations because of that fact.  

Dec 25 falls three days after the northern winter solstice.  Those three days were required in order to be certain that Sol Invictus had ceased his journey south and was 'reborn,' soon to return and banish the cold, bringing warmth for a new growing season, and with it, assurance of life for another year.   Some myths run deep in our psyches.