Is the Christmas tree a pagan symbol? The short answer is yes. In order, though, to find the full answer, one must look into the history of this icon of Christmas celebration.
“The use of evergreen trees, wreaths, and garlands to symbolize eternal life was a custom of the ancient Egyptians, Chinese, and Hebrews. Tree worship was common among the pagan Europeans and survived their conversion to Christianity in the Scandinavian customs of decorating the house and barn with evergreens at the New Year to scare away the devil and of setting up a tree for the birds during Christmastime” 
The claim, that the Christmas tree has its roots in paganism, is correct. However, what should be remembered is that evergreens holds a distinct place in the history of the Christian church as well.
An ancient tradition laced with fact and legend supposes that Boniface could have been the one who initiated the tradition in Germany. Boniface, appointed by Pope Gregory II as a missionary to the Germans in the early 700’s, was an ardent defender of Christianity and sought to destroy paganism in any way possible. Boniface, finding that the Germanic peoples were worshipping an oak tree devoted to Thor, “immediately took an axe to it. After only a few blows, the tree toppled to the ground, breaking into four pieces and revealing itself to be rotted away from within”
Legend has it that an evergreen grew from the trunk of the Oak of Thor. Boniface taught that the evergreen served as a symbol that the old pagan ways had died and was resurrected in the Christian faith.
Germany is credited with starting the Christmas tree tradition as we now know it in the 16th century when devout Christians brought decorated trees into their homes. Some built Christmas pyramids of wood and decorated them with evergreens and candles if wood was scarce. It is a widely held belief that Martin Luther, the 16th-century Protestant reformer, first added lighted candles to a tree. Walking toward his home one winter evening, composing a sermon, he was awed by the brilliance of stars twinkling amidst evergreens. To recapture the scene for his family, he erected a tree in the main room and wired its branches with lighted candles. 
Some Christians and unbelievers will argue that the Bible teaches against using Christmas trees to celebrate Christmas:
“Learn not the way of the nations, nor be dismayed at the signs of the heavens because the nations are dismayed at them, for the customs of the peoples are vanity. A tree from the forest is cut down and worked with an axe by the hands of a craftsman. They decorate it with silver and gold; they fasten it with hammer and nails so that it cannot move..” Jeremiah 10:2-4
However, if you read the next chapter, you can see that Jeremiah is speaking of wooden idols that have no causal connection to the world, not Christmas trees.
“Their idols are like scarecrows in a cucumber field, and they cannot speak; they have to be carried, for they cannot walk. Do not be afraid of them, for they cannot do evil, neither is it in them to do good.” Jeremiah 10:5
The Bible Answer Man Hank Hanegraaff, author of The Heart of Christmas, writes, “Christmas trees originated in Christian Germany two thousand years after Jeremiah’s condemnation of manmade idols. They evolved over time from two Christian traditions. One was a “Paradise Tree” hung with apples as a reminder of the Tree of Life in the Garden of Eden. The other was a triangular shelf holding Christmas figurines decorated by a star. In the sixteenth century. These two symbols merged into the present Christmas tree tradition. As such, the Christmas tree began as a distinctively Christian symbol and can still be legitimately used by Christians today as part of their Christmas festivities.
Yes, the Christmas tree may have been influenced by pagan symbols but there is nothing wrong for a Christian to own a Christmas tree. While the evergreen has some history in pagan religions, the evergreen holds an even deeper history in the Judeo-Christian tradition.
“Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come.” 2 Cor 5:17
Encyclopaedia Britannica 2012, http://www.britannica.com/plant/Christmas-tree).
131 Christians Everyone Should Know (Holman Reference), Galli & Olsen 2000, 365.
Hank Hanegraaff, The Heart of Christmas: A Devotional for the Season, 2009