What is the ruling on eating the food (rice, meat, chicken or cake) that is given to us by a Christian friend that he made for his birthday or for Christmas or the Christian New Year? What is your opinion on congratulating him by saying, “Insha Allaah you will continue to do well this year” so as to avoid saying Kull ‘aam wa antum bi khayr (approx. “season’s greetings”) or “Happy New Year” etc?.
It is not permissible for a Muslim to eat things that the Jews and Christians make on their festivals, or what they give him as a gift on their festivals, because that is cooperating with them and joining in with them in this evil, as is explained in question no. 12666.
It is not permissible for him to congratulate them on their festivals in any way whatsoever, because that implies approval of their festival and not denouncing them, and helping them to manifest their symbols and propagate their innovation, and sharing their happiness during their festivals, which are innovated festivals that are connected to false beliefs that are not approved of in Islam. See also question no. 47322.
And Allaah knows best.