then you also must not call the days of the week: Sunday (named for the sun god), Monday, (named for Mars), Wednesday, (named for Woden), Thursday, (named for Thor), and so on.
Many ancient churches were built over top of the ruins of a heathen worship spot, not so the church could fraternize with the heathen concepts, but to show Christianity taking dominion over the defunct heathen gods.
St Boniface, early Christian missionary to Germany, chopped down a "sacred tree" after stopping a human sacrifice near it. When the people saw that nothing bad happened to Boniface, they were able to relieve themselves of their bondage to superstitions. They chopped boughs off of "sacred" trees to put in their houses to show taking Christian dominion over the old pagan gods.
For us to put up a fir tree in our house to celebrate Advent and Christmas has nothing to do with superstition or worshiping evil spirits. No one uses his Christmas tree for such a purpose. The ancient superstitions are long gone and forgotten.