In my humble opinion Santa is an idol because that story takes Christ's rightful place at Christmas. The wonderful, "magical" story of Christmas is appealing and draws us all to want to know the truth, but that truth is only found through Jesus. Those who will not accept in their heart the real message of Christmas are forced to make something up. Just like those who are unwilling to make Jesus the Lord of their lives will resort to worshiping other things. Parents need to lie to their kids because they don't know the story of Jesus for themselves in a personal way. How can they share the wonderful blessings of Christ with their children when they have not experienced Him for themselves?
God created us all to be drawn to Himself. We all feel the "Magic" of Christmas and the warmth of thinking of others before ourselves. Kids need to know the truth behind those feelings. Unfortunately, that truth is just covered over with more lies as the kids get older and question what they've been told.
As for me and my house, there is no one before us but Jesus. We will serve our King and live in the fullness of His wonderful story and His amazing goodness. He has given Himself for us, to save us, rescue us, and deliver us into His love. I will tell that story. I want my kids to know this wonderful Christ and serve Him with all their hearts.