Christmas is the one day of the year that we celebrate the birth of Christ. However, just this one day is not definitive of the true spirit of the day and the season. I am reminded of the words Charles Dickens had Scrooge say when the great redemptive change came over him--"I will honor Christmas in my heart and try to keep it all the year."
We try to keep the spirit of Christmas alive in our hearts and lives the other 364 days of the year also. That is not hard, because we have the true spirit of Christmas dwelling within us, and that is Jesus Christ, the Son of God. He came, and we celebrate His birth one day out of the year. However, He came to bring us salvation, joy, and abundant life, and He didn't offer that to us for just one day, but for all eternity.
Yes, we love to decorate The Christmas House and show it to the people who come for tours. Yes, we love to sell the merchandise in our store, Santa's Texas Workshop. But our true purpose here is to share the love of Jesus Christ and to tell everyone that He came to save us! That salvation is available to all who believe in Him as being the Son of God, born of a virgin, who died a horrible death on the cross of Calvary, and then rose again, coming back to life on the third day. His Resurrection gives us the great hope of our own resurrection when He comes back again!
That is why we believe that crosses are a part of Christmas and it's okay to put them with Nativity scenes. One is not complete without the other.