Red as Sin
Perhaps, upon reading Andersen's tale, "The Red Shoes," it was fairly obvious to you that there'd be some symbolism involving Karen's shoes. Well, we already know you're smarter than us, so go ahead, gloat. Just not too much, or Andersen might roll over in his grave.
In "The Red Shoes," Karen first gets her hands on a pair of shoes made "from scraps of red material" that are a gift from a widow (35.2). She wears these shoes to her mother's funeral even though "they weren't the proper color for mourning" (35.3), since she didn't have any other shoes. Translation: Karen comes from a dirt-poor family, and when that's the case, you've gotta make do with what you have.
When Karen gets lucky and is adopted by a rich lady, she sees a princess wearing "the loveliest red shoes" (35.6), which inspires her to lust after some red shoes of her own. Karen persuades the widow to buy her a pair, and since the widow's eyesight isn't too good, Karen manages to wear them to her confirmation.
But there's a problem. Not only is it "improper… to have worn red shoes in church" (35.12), but the red shoes also take Karen's mind off godly matters. In fact, she's so vain about her red shoes that she deserts the widow when she gets sick, just for a chance to go party in her red shoes.
We know what happens next. Karen is cursed to dance endlessly in the shoes, and she has to beg an executioner to chop off her feet just so she doesn't die from dancing nonstop. So red shoes = vanity = life-threatening. So, unless you want to die or hobble around for the rest of your life feetless, you better shove your red sneaks in a closet and opt for a humbler color. Unless you plan on later telling God that you feel super duper awfully bad about how much you love those red sneakers. (Or your name is Dorothy.)
Red for Redemption?
You see, there may be a slightly more positive take on the red shoes than what we've presented so far. Sure, the red shoes cause Karen to get her feet chopped off. And then she continues to be haunted by the ghastly image of these shoes with her dismembered feet still inside them every time she tries to go to church.
But when Karen finally repents "in the depth of her heart" (35.40), she's able to honestly beg God for mercy. And that's when she has a vision of church and subsequently dies and goes to heaven. So, in a strange, roundabout kind of way, the red shoes were the cause of both Karen's suffering and salvation. Without them, she might've just stayed another arrogant, superficial person forever. And, knowing Andersen, that ain't the kinda girl who'd get into heaven.
Being able to give up one's red shoes—that is, one's pride or vanity—tends to lead to good things for Andersen's characters. In "The Snow Queen," when Gerda goes looking for Kai, she goes down to the river and asks it if it's taken her playmate. To get an answer, "she took her treasure, her new red shoes, and threw them out into the river" (29.53).
Of course, the river didn't have Kai, so this sacrifice doesn't actually bring Kai back. Yet, Gerda's willingness to sacrifice her beloved red shoes is a sign of her earnestness about the search, and that open-heartedness eventually reunites her with Kai.
We're not necessarily advocating that every Shmooper goes out and buys a pair of red kicks as a ticket to salvation. What we're saying here is that it's your attitude toward those shoes, yourself, the people in your life, and, well, just about everything, that matters. Life is short (especially for most of Andersen's characters), so it pays to believe in something other than yourself.