I've long entertained a dubious regard for the practice of lying to children about the existence of Santa Claus. Parents might claim that it serves to make children's lives more magical and exciting, but as a general rule, children are adequately equipped to create fantasies of their own without their parents' intervention. The two reasons I suspect rest at the bottom line are adherence to tradition, and finding it cute to see one's children believing ridiculous things.
Personally, I considered this to be a rather indecent way to treat one's own children, and have sometimes wondered whether a large proportion of conspiracy theorists owe their origins to the realization that practically all the adults in the country really are conspiring to deceive children for no tangible benefit. However, since I began frequenting this site, I've been exposed to the alternate viewpoint that this realization may be good for developing rationalists, because it provides children with the experience of discovering that they hold beliefs which are wrong and absurd, and that they must reject them.
So, how did the Santa deception affect you personally? How do you think your life might have been different without it? If your parents didn't do it to you, what are your impressions on the experience of not being lied to when most other children are?
Also, I promise to upvote anyone who links to an easy to register for community of conspiracy theorists where they would not be averse to being asked the same question.
I was taught to believe in Santa Clause by both parents (atheist father and catholic mother).
One particular year (I think I was five) my mother told to me to pray the night before Christmas to get everything I wanted for Christmas. And I did. And I got everything I wanted for Christmas. Awesome! This prayer thing apparently really worked. (I had also written a letter to Santa a few weeks earlier)
The next year, my dad suggested I write another letter to Santa. I said "nah, I tried this prayer thing last year and it worked pretty well." Dad said "um....."
I prayed, fully expecting to get everything I asked for. I got maybe a third of it.
That was when I stopped believing in God.
A few years later, during Summer (I think I was seven) I asked my dad where the universe came from, and he showed me a book called "The Universe" which explained how huge clouds of gas had condensed to make the sun and planets. I asked my dad further questions about why the outer planets were gaseous ane the inner planets were solid, where black holes came from and a bunch of other stuff. And I was like "holy crap, the universe is awesome and supremely elegant and logical and stuff."
A few months later it was Christmas time, and I suddenly realized I didn't believe in Santa any more. Not because of any particular anti-Santa evidence, but just that he didn't really fit with the otherwise orderly and logical nature of the universe. (It was a few years before mounting empirical evidence led to finally give up the belief completely. Until then it was more of a "I notice that I am confused" thing).
That said, even after realizing I was being lied to, I loved the idea of Santa Clause and was glad to have that magic in my life for as long as I could. In fact, I think he teaches an important lesson that any atheist should be perfectly fine with teaching their child: magic is fun, but it isn't real, and you can't trust authorities to always tell the truth.