Mary and Jesus were leaving the city to hide from King Herod.They grew very tired so they stopped in a cave to rest. The soldiers came by but did not look into the cave because it was covered in cobwebs. That night as they slept a spider had covered the entrance to the cave to keep them safe. When Mary and Jesus awoke the cobwebs shimmered in the morning sun and they new God had kept them safe. So when you see Tinsel on a tree it symbolizes the spiders web that saved Mary and Jesus.