Christmas trees are in Catholic churches, but they are not put up until just before Dec. 24th and are never lit until Christmas Eve Mass, and then only during the twelve days of Christmas - until the Feast of the Epiphany.
In the Catholic church Advent lasts for 4 Sundays until Christmas Eve. Then the Christmas Season is celebrated from Dec. 24 Evening onward. For this reason, we are not singing Christmas carols right now - but rather Advent songs of the long awaited coming of the Lord Jesus, the Messiah.
I am amazed that many of the Non-Catholic, non-Greek Orthodox , Christian denominations are already singing Christmas Carols during their Sunday worship services. It’s OK for a Christmas pageant for the kids, but is not really liturgically proper. After all, the Birth of Jesus is celebrated on Dec. 25th. Just my 2 cents worth!
Even though EVERYONE (AFAIK) knows that He probably was NOT born on or around that date!