Somehow I missed the reply of Nrsimha Kavaca Prabhu from the Deity Ministry in my pile of mail. Just for your information he wrote: "Regarding Christmas - it is not a Gaudiya festival. This festival was previously followed at the farm in Hungary. Sivarama Maharaja has since stopped this when it was brought to his attention that it was not an appropriate deity festival. Based on consultation with other senior devotees it was concluded that it is not appropriate for us to observe such festivals. Better that we focus on what has been given to us in the scriptures and by our acaryas."
see more http://jornalharekrsnabrasil.blogspot.com/2011/12/radha-and-krishna-as-mr-mrs-santa-claus.html