I am afraid you are wrong, but we will just agree to disagree. The modern iconography of Santa Claus is nothing more than an advertisement and the irony that people take issue with those who refer to our December celebrations as Festivus is striking!
While Saint Nicholas was originally portrayed wearing bishop's robes, today Santa Claus is generally depicted as a plump, jolly, white-bearded man wearing a red coat with white collar and cuffs, white-cuffed red trousers, and black leather belt and boots. This image became popular in the United States and Canada in the 19th century due to the significant influence of caricaturist and political cartoonist Thomas Nast.
In 1821, the book A New-year's present, to the little ones from five to twelve is published in New York. It contains Old Santeclaus, an anonymous poem describing an old man on a reindeer sleigh, bringing presents to children. Some modern ideas of Santa Claus seemingly became canon after the publication of the poem "A Visit From St. Nicholas" (better known today as "The Night Before Christmas") in the Troy, New York, Sentinel on December 23, 1823 anonymously; the poem was later attributed to Clement Clarke Moore. Many of his modern attributes are established in this poem, such as riding in a sleigh that lands on the roof, entering through the chimney, and having a bag full of toys. St. Nick is discribed as being "chubby and plump, a right jolly old elf" with "a little round belly", that "shook when he laughed like a bowlful of jelly". The reindeer were also named: "Now! Dasher, now! Dancer, now! Prancer, and Vixen, On! Comet, on! Cupid, on! Dunder and Blixem".
One of the first artists to define Santa Claus's modern image was Thomas Nast, an American cartoonist of the 19th century. In 1863, a picture of Santa illustrated by Nast appeared in Harper's Weekly.
In the United Kingdom, Santaor Father Christmas -- was historically depicted wearing a green cloak. More recently, that has been changed to the more commonly known red suit. One school in the seaside town of Brighton banned the use of a red suit for erroneously believing it was only indicative of the Coca-Cola advertising campaign. School spokesman Sarah James said: "The red-suited Santa was created as a marketing tool by Coca-Cola, it is a symbol of commercialism." In reality, the red-suited Santa was created by Thomas Nast.
Images of Santa Claus were further popularized through Haddon Sundbloms depiction of him for The Coca-Cola Companys Christmas advertising in the 1930s.The popularity of the image spawned urban legends that Santa Claus was invented by The Coca-Cola Company or that Santa wears red and white because they are the colors used to promote the Coca-Cola brand. Historically, Coca-Cola was not the first soft drink company to utilize the modern image of Santa Claus in its advertising White Rock Beverages used Santa to sell mineral water in 1915 and then in advertisements for its ginger ale in 1923. Although the Coca-Cola advertising campaign had the effect of popularising the depiction of Santa as wearing red and white, in contrast to the variety of colours he wore prior to that campaign; red and white was originally given by Nast. [Multiple sources].