I'll give my usual caveat that I'm not a qualified responder, but I want to correct some of the points made in other comments.

The image (In the United States) of Santa Claus as a man with white beard and red fur lined clothes was pretty well established by the last quarter of the nineteenth century. Thomas Nast was pretty integral to creating this image, and you can examples of his work for Harper's Weekly here:

https://www.metmuseum.org/art/collection/search/822569?sortBy=Relevance&ft=Thomas+Nast&offset=0&rpp=40&pos=11

https://www.metmuseum.org/art/collection/search/429261?sortBy=Relevance&ft=Thomas+Nast&offset=0&rpp=40&pos=36

https://www.metmuseum.org/art/collection/search/822566?sortBy=Relevance&ft=Santa+claus&offset=0&rpp=40&pos=8

http://www.printsoldandrare.com/thomasnast/347xmas.jpg

https://www.rarenewspapers.com/view/174936

And from the published work A Visit from Saint Nicholas:

https://www.americanantiquarian.org/Exhibitions/Christmas/nast.htm

I don't think Thomas Nast's contribution to the visual language of modern Christmas can really be overstated. While Haddon Sundblom's (The illustrator of Coca-Cola's initial Christmas ad campaign) depictions of Santa Claus are certainly very influential, he readily admitted that he drew inspiration from Thomas Nast and Jenny Nyström (a famous Swedish postcard illustrator) .

However, the transition of Christmas as a more general holiday that included lots of drinking, feasting partying, demanding gifts or drinks from your employer was well underway before this. Due to fears of social unrest and changing attitudes, authorities and cultural leaders encouraged an image of Christmas as a sedate holiday- celebrated largely at home (in private)- that focused on children.

So, to your question about how secular companies, specifically Coca-Cola, created the images of modern Christmas: No, Coca-Cola didn't originate the modern American visual language of Christmas. Have Sundblom's illustrations had a massive impact since then? Yes. Did another secular company create the current American image of Christmas? If anyone, it was Harper's Weekly.

To your question about whether Coca-Cola or other companies created the modern American tradition of Christmas, and its accompanying celebrations and rituals? Also no, that shift had occurred before Coca-Cola came into existence.

I'd suggest reading Stephen Nissanbaum's The Battle for Christmas, which is my source for this.

Nissenbaum Stephen. 1996. The Battle for Christmas. 1st ed. New York: Alfred A. Knopf.

EDITED: Spelling and grammar.