Non-Christians claim that Christmas trees are a religious symbol of Christmas. Is a Christmas tree really a religious symbol of Christmas equal to a Nativity scene?
It depends on how religious symbol is defined. If it means anything to which religious significance can be attached, then yes, because many Christians have attached religious significance to the Christmas tree (e.g., the Tree of Life, both in Eden and on Calvary). But if a religious symbol of a holiday is considered a tangible object intrinsically attached to that holiday, and without which the holiday wouldn’t be the same, then no, because the celebration of Christmas does not require Christmas trees. Christmas trees are a decoration that Christians incorporated into their celebration of the holiday over the centuries. They did not become widespread in the English-speaking world until German relatives of the British royal family brought the custom to Great Britain in the 18th and 19th centuries. Christians justified the custom on religious grounds by explaining that the evergreen tree can symbolize eternal life. Even today in many traditionally Catholic countries, far more emphasis is placed on the much older Christian custom of erecting Nativity scenes, a tradition attributed to St. Francis of Assisi (1181-1226). In short, although Christmas trees are a beloved custom in much of the English-speaking world, they are not necessary to the celebration of the holiday and are not nearly as symbolic of the holiday as the crèche. If it is agreed that a religious symbol should be understood to mean a tangible object intrinsically attached to that holiday, then Christmas trees are to Christmas what dreidels are to Hanukkah—a beloved custom but not a religious symbol.