Lying to Children about Santa Claus

At work the other day a co-worker told me that she told her son the truth about Santa Claus and the boy, who was almost a teenager, was devastated. The son cried for a long time and accused his parents of cruelty. When the son asked why the mother did this to him, the mother said, "When you have kids, you'd do the same."

I asked this mother why she lied to her child like this and she said, "We're Christians, so it's part of our tradition to celebrate Christmas."

This doesn't make any sense to me. Look at what the Bible says:

Lying lips are an abomination to the Lord.
-Proverbs 12:22

If the Bible claims that lies are an abomination to the Lord, then why would a Christian knowingly lie to his or her child about Santa Claus? And what does Santa Claus have to do with Christianity? There is no mention of Santa Claus, flying reindeer, or Christmas trees in the Bible.