As I was in the forth grade in the primary school, the official communist history books in Poland claimed that Christ never existed and that he was an imaginary person invented by Christians (they did not bother about who invented Christians by the way). Well, in the meantime even communists had to acknowledge that Christ existed. Especially after recent studies and investigations of the Shroud of Turin, witnessing Christ's crucifixion and resurrection.
Till the present day many atheists do not know that even the graves of the Three Kings were discovered on the territory of the former Persia which was a surprise even to many Christians.
Many believed that, based on the mentioning of the census in Roman empire, that Christ was born much later than we start our calendar. Yet later on it has been discovered by historians that the earlier census mentioned in the Bible really took place so the dating is correct.
Jehovah Witnesses believe seriously that Christmas is celebrated during the wrong season because (at least years ago) on December 24th we have usually snow and frost, but it is written in the Bible that there were shepherds pasturing their flocks when Jesus was born. They cannot grasp that the climate in Palestine is much different from that in Poland.
Actually Saint Nicolas was a bishop of Myra and became famous for what he is now commemorating: for giving gifts to the poor inhabitants of his diocese.
This fake news is spread in the main stream media by many uneducated journalists nowadays.
But actually this is the same date - the difference is in the assumed calendar: the Julian and the Gregorian one. When in Julian calendar we have 24th December, then in Gregorian one we have January 6th. The difference actually results from a reform when it was noticed that the Earth does not make a round around the Sun within 365 and 1/4 of a day but in a little shorter time. So it was observed that with the old Julian calendar the seasons started to move out of their old time frame. Therefore in the Catholic Church the calendar reform was introduced by the Pope Gregory the Great. It was however not followed by orthodox Churches so the difference occurs and will be growing 3 days in each 400 years.
Actually Christmas was celebrated as early as in the 2nd century when there was a sharp conflict between pagans and Christians so that taking over of the pagan celebrities would be unconceivable. Rather, the people investigated the historic evidence to identify the date as accurately as possible and around the year 200 AD the date was settled. In fact the date when Jesus was conceived was interrogated and then 9 months were added. (And guess why those people without sex education at school added nine months to the date of conception).
See also: Christmas Traditions in Poland