Mince pies were originally filled with meat, such as beef or lamb, rather than the dried fruit mix as they are today. They were first made in an oval shape to represent the manger that Jesus slept in as a baby, with the top representing his swaddling clothes. Now they are normally made in a round shape and are eaten hot or cold.
One legend tells that the original recipe for mincemeat pie was filled with religious symbolism. The pie was supposed to have 13 ingredients, symbolizing Jesus Christ and his 12 apostles. The ingredients had to be stirred from east to west to show the route of the Three Wise Men, or Magi. In addition, the pie had to contain three Middle Eastern spices--cinnamon, cloves and nutmeg--to represent the three gifts the Magi gave to the Christ Child. Although recipes varied, the meat may have been combined with pepper, salt, saffron, suet or marrow, vinegar, prunes, raisins, currents, dates, and orange peel.
On Christmas Eve, children in the United Kingdom often leave out mince pies with brandy or some similar drink for Father Christmas, and a carrot for the reindeer. Interestingly, there is even a Mince Pie Club! http://www.mincepieclub.co.uk/.
Trivia: Eat a piece of mincemeat pie every day between Christmas and the Twelfth Night (January 6th) and you will have 12 months of good luck. It's even better if you can eat the pies at a different house each day!