lamont william went to get to the bottom of the christmas ideas. >> reporter: through the ages, christmas has evolume toughed what we know it as -- has evolved to what we know of today. what is fact you and what are the smiths? >> there's so many questions that i think had fascinating answers and i will write a book which i ask 50 questions. >> reporter: that raised from the birth of jesus christ to kwanza. joe says early christians didn't originally celebrate the birth of jesus. but they don't get to this-- >> but they don't get to this until the 4th century and no one speculates for when jesus is born until around 200. it doesn't matter. it's not in matthew or luke. no notice of christmas is a holiday as a celebration until the 4th century. >> reporter: what about the jolly old elf santa claus? how did he get in christmas. >> st. nicholas who lived in the 4th century ad santa claus is the invention of a handful of people in 19th century new york. essentially, they take old dutch center cloth who is derived from st. nicholas, and they essentially resuscitate him. they are the one who is