Christians celebrate Christmas for what it represents rather than the day itself.
To begin with, Christmas is something started by the Catholics wrongly... and due to most protestants branching from Catholics, these traditions are carried forward.

So unfortunately, Christmas has been wrongly commercialized but in fact there is NOTHING in the bible that asks Christians to celebrate Christmas..

The new covenant rest is not about physical resting from work but a rest of assurance in the salvation of God.

If you think I don't understand this, read whole chapter of hebrews 4.

Why it starts talking about "promises of God", that is No.1 then ends with a High Priest who empathize with our weaknesses, That's Point 2 and why it talks about good news proclaimed to them did not go in because of their disobedience?

What has promises of God and High Priest and good news, that they cannot go in has to do with rest from work if the context were such?

Do you know? I'm asking because you seem to imply "Many don't understand". And before you answer, think carefully, because this requires theological understanding.