While it is true that some of the symbolism we hold dear might have pagan origins, this does not change the fact that we have fully Christianized them, "re-baptizing" them into things that point the way to Christ. Prior to his Incarnation, everything outside of the Jewish faith was pagan - it would be insane to stop using nearly everything because at one time prior to our knowledge of Christ we used certain foods or practiced certain customs. When we "test all things" in order to find the truth contained therein, then we can take a deep breath and say, "This is a tool (or event) that leads us to Christ." And, as St. Paul said, once we test something, "hold fast what is good." So, for Catholics the symbolism we love at Christmas isn't a continuation of pagan holidays, but re-baptized symbols that point the way to Christ.
It is true that many pagans worshiped trees - there are many today who do just that, whether they realize it or not. But this (mainly Germanic) tradition of tree worship took a significant change in direction in the 700s when St. Boniface chopped down Germany's "holiest" tree, the Oak of Thor. A small fir tree was starting to grow out of its base and St. Boniface said, "This humble tree's wood is used to build your homes: let Christ be at the centre of your households. Its leaves remain evergreen in the darkest days: let Christ be your constant light. Its boughs reach out to embrace and its top points to heaven: let Christ be your comfort and your guide."
By the Middle Ages, Christmas plays would be held on Christmas Eve, which in those days was marked on the liturgical calendar as the feast day of Saints Adam and Eve. A tree would be used in the play, called a Paradise Tree and often decorated with apples, and this symbolized the tree in paradise of whose fruit we ate; it also doubled as the Tree of Life, of whose fruit we are promised to eat at the end of time. Much like how we have Advent wreaths and nativity sets in our homes, people desired to have this tree brought into their homes, as well. By the 15th Century, having a Paradise tree in your home was a common practice in certain parts of Europe. In the 1500s, Christmas trees were being decorated with candles to symbolize the light of Christ, and by the 1800s this custom was firmly established throughout France, Germany, and Austria. Needless to say, it spread throughout the world and symbolizes all the trees of our spiritual heritage: "the original Tree of Paradise, the burning bush which spoke to Moses, the branch of Jesse from which Jesus was born, the life-giving tree of the cross of Christ, and the tree which St. John the Apostle saw in the Book of Revelations whose leaves have medicine for the people and which yields fruit each month for the healing of the nations."
We also see in Christmas trees, often taken from evergreens (pine, fir, etc.), a symbolism that reminds us to stay steadfast in the faith; since evergreens withstand the harshness of the winter, they persevere, as we should persevere in our faith. There is also the thought that Christmas trees can remind us of Christ's death and resurrection (the tree is chopped down, but then rises again in our homes).
We will see this "hardy steadfastness" of the various plant life we use at Christmas as a common theme.
Other Christmas Plants and Flowers
Laurel is sometimes used in Christmas wreaths. The plant was once used in Roman times to symbolize victory and the plant began to symbolize Christ's victory over death. A wreath of laurel was a Roman symbol of victory and, like the plant, wreaths began to be used at Christmas to symbolize Christ's victory over death. Not having a beginning nor end, wreaths symbolize God's reign, as well as everlasting life. Ivy, since it grows by clinging onto other things, became a symbol at Christmas that represents our reliance on God, that we must cling to him. Holly (the green leaves with their red berries) became a symbol of the burning bush, as well as Christ's crown of thorns. Poinsettias are actually a Christmas tradition from the New World; the shape of the flower is supposed to represent the star of Bethlehem, and the red color is supposed to represent the blood of Christ (white flowers represent his purity).
The Yule Log
The Danish ruled over England in the 11th Century and they left behind some of their words and traditions, like a word they used for Christmas: Yule. By the 13th Century, it was in the common vernacular in England and Scotland to refer to Christmas as Yuletide. For Anglicans and Catholics, this seems familiar to us because we use similar words, such as Christmastide, Eastertide, Embertide, Passiontide, Whitsun tide, and so on. There is always the charge that the Yule log and the word yule is associated with Scandinavian paganism, but the leading British historian on paganism, Ronald Hutton, said, "Nothing certain, however, is known, and there is equal doubt over whether it was originally attached to a midwinter festival which preceded the Christian one," so they don't know for sure; I guess it depends on your bias. At any rate, the yule log is a large log intended to burn for the twelve days of Christmas (from Christmas till Epiphany).
The other day I was wondering how Santa Claus got the moniker "Kris Kringle". As it turns out, it was another Americanization of the traditions of other lands. St. Nicholas, as we discussed last year, was a real person - a bishop from the 300s. Devotion to St. Nicholas spread throughout Europe and the Middle East and he became known to the Dutch as Sinterklaas; we Americanized the pronunciation to be Santa Claus. Well, Kris Kringle is sort of the same thing. In many Catholic areas (like Germany, the Czech Republic, Croatia, Austria, Italy, Liechtenstein, Luxembourg, Portugal, Switzerland, Slovakia, Hungary, France, and Upper-Silesia in Poland), Christmas gifts are brought by the Christ Child. This figure was adopted because Catholic nations were feeling uncomfortable about the secularization of St. Nicholas into Santa Claus. Called 'Christkindl' by the Dutch, the Americanized version of the name became 'Kris Kringle' - in America, the name became an alias of Santa Claus and by modern times, and in Europe the figure 'Christkindl' is no longer the Christ Child, but is now played by a woman dressed up like a queen, so sadly their attempts to fight the secularization of Christmas symbols has been a failure.
The Creche, or Nativity Scene
St. Francis of Assisi (b. 1181, d. 1226) started the first nativity scene. By the time of St. Francis, Islam had spread over a large portion of the world, including areas that were at one time Christian. As part of devotion or penance, many Christians traveled to the Holy Land on pilgrimages, but the Muslims were often robbing or killing pilgrims. Eventually, the Holy Land would become off-limits to Christians; St. Francis' solution was to bring the Holy Land to Europe! For Christmas he assembled the manger scene, allowing Christians to pray in devotion to the place of Christ's birth without making the harsh and dangerous journey to Bethlehem. (In a similar way, the Stations of the Cross, which we pray during Lent, is also a Franciscan devotion he created for the same reason).
These are just some of the symbols we've come to embrace at Christmastime. Regardless of their origin, they've become symbols of our faith and remind us at every glance that our Lord is with us and he is victorious. As the evergreens and holly survive the harsh winters of the north, we are called to survive this harsh winter on earth until the Lord, victorious over death and the devil, will reign in power and glory forever and ever. Amen!