Ruling on the Muslims celebrating at the time of Christmas and decorating their homes with balloons


What do you say to Muslims in the United Kingdom who celebrate at Christmas time by holding dinner parties in their houses on Christmas or afterwards, for their Muslim families, such as preparing roast turkey and the other dishes of the traditional Christmas dinner, and they adorn their houses with balloons and paper chains, and they do the “secret Santa” tradition, whereby each relative brings a gift for one of the people present and these gifts are brought to the party to be given to the one for whom he bought it, without the recipient knowing who he is. [“Secret Santa” is a new, growing custom among non-Muslims who celebrate Christmas, and is in accordance with their belief in the myth of Santa Claus].
Is this action regarded as halaal or haraam, if no one is attending this party except Muslims (relatives and family members)?.