What's wrong with that?
I understand that Christians slapped their own mythology onto a preexisting festival and claimed it for themselves, and now some of them make a fuss about non-Christians who decide to celebrate at that same time of year if that's what you mean.
I have never heard of fruitcake being mocked - is that an American thing? There is a saying "Nutty as a fruitcake", because (UK) fruitcakes often contain nuts such as almonds, but it's not the cake that is being mocked.
see how that sounds?
It’s Christmas cake or Dundee cake or Christmas pudding. ‘Fruit cake’ is not a seasonal foodstuff as such. It is eaten all year round.
Since when was eggnog a Christmas tradition? (Except, maybe, as some kind of purgative!)