Today Christmas seems very commercialized and flamboyant, and I was wondering to what extent this was caused by the desire to unite against those "godless soviets". I'm not too familiar with how soviet citizens would have celebrated Christmas, other than it would've been celebrated on the Eastern Orthodox day, but I wonder if some of the over the top decorating and massive commercialization we see today is a result of American pride more than "Christmas spirit", although now it seems to be more tradition than anything else.
Did Christmas always have the sense of unity and togetherness that we recognize today? Would it have been celebrated the same way in 1880's when the US was not involved in major international conflicts versus in the 1980's?
I will let others write about American Christmas, but I can provide a little background about Russian/Soviet Christmas.
Christmas was originally celebrated as a religious holiday on January 7. New Years as a holiday was introduced by Peter the Great. Both holidays were relatively minor until Russia began importing Germanic festive customs like bringing fir trees indoors and giving presents to children in the mid-19th century. The adoption of these customs was from Prussian / German royal family members marrying in to the Russian Romanov dynasty (Albert marrying Victoria and bringing the same Christimas customs caused the same adoption in the English-speaking world at the same time).
After the Bolshevik revolution in 1917, the Soviet government banned public religious holidays, and also updated the calendar from the Julian one to the Gregorian one. But attempts to create a brand new youth holiday in place of Christmas didn't get very far, so in 1935 Stalin brought back Christmas customs, but with a twist: they were now on New Year's, not January 7.
Since then, New Year's has been celebrated as the Soviet / Russian version of secular Christmas, complete with the trees, lights, presents and Dyed Moroz ("Father Frost", the Russian version of Santa Claus). It's a universal holiday that pretty much all nationalities and religions participated in. Orthodox Christmas (January 7) since the fall of communism is a holiday, but a more religious one and is much overshadowed by New Year's (confusingly, January 14 is "Old New Years" because it is the start of the Julian calendar year, but even less people celebrate that).
So in conclusion: a lot of the nonreligious and commercial aspects of Western/American Christmas were present in the USSR during the Cold War, just on January 1, instead of December 25.
Source: How Soviets Came to Celebrate New Year's Like Christmas, and Why Russians Still Do