And that...is an absolute.
Nothing wrong with an absolute if it is true. Does the Bible reavel the date or month of Christ birth? If the answer is no then telling people that he was born on December 25th is a lie. Lying is a sin and telling people a lie about God’s word can do a lot of damage.
If one wants to remember Christ or his birth on December 25th that is fine it is always good to remember Christ but there is no good to come from telling a lie.