People are very fond of quoting Romans 14:5 to justify nearly anything they want to do: "One person esteems one day above another; another esteems every day alike. Let each be fully convinced in his own mind."
But they overlook the context: "He who observes the day, observes it to the Lord; and he who does not observe the day, to the Lord he does not observe it. He who eats, eats to the Lord, for he gives God thanks; and he who does not eat, to the Lord he does not eat, and gives God thanks. For none of us lives to himself, and no one dies to himself. For if we live, we live to the Lord; and if we die, we die to the Lord. Therefore, whether we live or die, we are the Lord’s." Romans 14:6-8
Does this give us liberty to steal, or murder, or commit adultery? Of course not. The idea is that whatever we do we do it unto the Lord. So the question is: Is the Lord glorified when we say we're celebrating His birth and mix in all kinds of pagan traditions and worldly practices? Does that sound like it's "unto the Lord" or unto us?
I'd be fine with celebrating the Lord's birth in a way and on a day that strips away all the worldly and pagan traditions.