When Oliver Cromwell came to power in England, Catholics were not permitted to practice their faith openly. Tradition holds that Catholic parents developed "The Twelve Days of Christmas" to teach children their beliefs.
The partridge in a pear tree represents Jesus (the partridge will sacrifice its life to save its young).
Two turtle doves: The Old and New Testaments
Three French hens: Faith, hope, and charity, or the three gifts of the Wise Men
Four calling birds: The four Evangelists--Matthew, Mark, Luke, and John
Five golden rings: The first five books of the Old Testament
Six geese a-laying: The six days of creation described in Genesis
Seven swans a-swimming: The seven gifts of the Holy Spirit (wisdom, understanding, counsel, strength, knowledge, piety, and fear of the Lord)
Eight maids a-milking: The eight Beatitudes
Nine ladies dancing: The nine choirs of angels (Seraphim, Cherubim, Thrones, Dominions, Virtues, Powers, Principalities, Archangels, and regular angels); or the nine fruits of the Holy Spirit (love, joy, peace, kindness, goodness, patience, gentleness, faithfulness, and self-control).
Ten lords a-leaping: The Ten Commandments
Eleven pipers piping: The eleven faithful Apostles
Twelve drummers drumming: The twelve points of belief in the Apostles' Creed