Yes, the mythical Santa Claus has pagan connections. Yes Christmas time has pagan roots. No, Jesus was not born on the 25th. Your point is? Some fellow atheists around the web make an annual point of touting these facts whenever Christmas time comes around, perhaps in the hope it will help diminish or delegitimise it in the public's mind. Or perhaps as a way of celebrating or consolidating their own non-belief with a little anti-Jesus groupthink - killing Christmas to keep the world safe for rationalists, as it were. I think they need to take a deep breath and relax. While I share their concern about the corroding effect religion can have on reason, it would be unwise to lose sight of the greater good the festive season represents. The historical origins of Christmas are not important, and one's belief system or the lack thereof shouldn't obstruct the bigger picture.
Christmas time matters because it is the single global occasion when the sentiments of peace and good will are embraced in momentary contrast with an otherwise turbulent year. Christmas is thus an atmosphere; it is a mood made manifest by the original moral teachings of the Judaic humanist, Yeshua the Nazarene, whose faith in brotherly/sisterly love and compassion for the poor still remain universal beacons of moral light. His ethics, with or without their religious clothing, amount to a humanist crucible, a test of selflessness against self indulgence; giving rather than expecting. Seen in this light, with its priority on sharing and spreading love, Christmas is beyond the great debate between theists and atheists. You don't have to be a Christian to appreciate Christmas. So just enjoy it and put aside the battles for another time. Merry Christmas!