The spiked leaves of the holly plant are used at Christmas to represent Christ's crown of thorns. Because even as we celebrate His birth, we also remember and celebrate His death, by which we were saved.
This is also why in art, you tend to see the infant Christ with His arms spread in anticipation of His crucifixion.
2. Christmas colors: Green
Why do we use evergreens at Christmas? In our homes we decorate with trees, boughs, garlands, and wreaths. These undying plants represent eternal life.
3. Christmas colors: Red
Red, as in the berries on the holly plant, or the bows we tie around our wreaths represents Christ's blood, shed for us [and for many, unto the remission of sins -- can't help quoting the Mass here!].
Before electricity, people would place candles on their trees, or a bright flame in each window. Now we wrap our homes and trees with colorful electric bulbs. These lights represent Christ, the Light of the World, as well as the bright star which led adorers to the place of his birth. This is also why a star tree-topper is the most common type.
5. Christmas Bells
I feel like these are a less common decoration than they once were, but Christmas bells are intended to call to mind that church bells that announce Christ's birth, and call us to prayer.
The first people to give gifts at Christmas were the Magi, arriving twelve days after Christ's birth 9Feast of the Epiphany, January 6th0. For centuries, Christians have imitated this practice. I have read that in the past, gift-giving was just directed at children. And they would receive just a few small items - maybe some candy, an orange, perhaps a small toy or coin. These days, adults have jumped into the gift-giving full-force, and I don't think anyone could argue when I say that it often gets out of control. People give much more extravagant gifts today than our ancestors would have considered decent. The consumerism surrounding Christmas is sometimes disgusting, and so opposite of the true meaning of the day. I know that as soon as I was old enough to suddenly feel an "obligation" to buy gifts for many friends and family members (with my own scant supply of cash), the Advent season took on a definite stressfulness that should really have no place in this time of joyful anticipation.
7. Secular symbols
Santa Claus, reindeer, jingle bells, snowmen, snowflakes....most of these things are tied up with the Santa Claus legend, or the fact that Christmas (in the northern hemisphere at least) falls during the winter. I don't think there's anything wrong with this side of Christmas, except when it detracts and distracts from the true meaning of why we're celebrating.
See more Quick Takes at Conversion Diary