It is not permissible for any Muslim to join in the festivals of the kuffaar, whether by attending the festivities or enabling them to hold their celebrations, or selling any goods or products that have to do with these festivals. 

Shaykh Muhammad ibn Ibraaheem (may Allaah have mercy on him) wrote to the Minister for Trade, saying: 

From Muhammad ibn Ibraaheem to His Excellency the Minister for Trade, may Allaah preserve him. Peace be upon you and the mercy of Allaah and His blessings. 

We have been told that last year, some traders imported gifts for Christmas and the Christian New Year, including Christmas trees, and that some citizens bought these and gave them as gifts to Christian foreigners in our country, joining them in this festival. 

This is an evil action which they should not have done. Undoubtedly you know that this is not permissible, and you are aware of what the scholars have said about there being scholarly consensus on the prohibiton on joining the kuffaar, mushrikeen and people of the Book in their festivals. 

We hope that you will issue a ban on these gifts that have been brought into our country and other things that come under the same ruling and are things that are unique to their celebrations. 

Fataawa al-Shaykh Muhammad ibn Ibraaheem, 3/105. 

Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allaah have mercy on him) was asked: 

Some Muslims join the Christians in their celebrations. What is your advice? 

He replied: 

It is not permissible for any Muslim man or woman to join the Christians, Jews or other kaafirs in their festivals, rather that must be avoided, because “Whoever imitates a people is one of them.” The Prophet (peace and blessings of Allaah be upon him)  warned us against imitating them and adopting their ways. So the believer, man or woman, must beware of that; it is not permissible to help them in doing that in any way, because these festivals are against sharee’ah, so it is prohibited to take part in them or to cooperate with the people who are celebrating it, or help them in any way, whether by helping them to serve tea or coffee or in other ways such as providing vessels etc, because Allaah says (interpretation of the meaning): 

“Help you one another in Al‑Birr and At‑Taqwa (virtue, righteousness and piety); but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment”

[al-Maa'idah 5:2] 

Joining in with the kuffaar on their holidays is a kind of cooperating in sin and transgression. 

Majmoo’ Fataawa al-Shaykh Ibn Baaz, 6/405 

In a statement issued by the scholars of the Standing Committee concerning joining in celebrations of the Millennium, they said: 

… It is not permissible for a Muslim to cooperate with the kuffaar in any way with regard to their festivals, such as announcing and publicizing their festivals, including the Millennium mentioned above, or promoting them by any means, whether that is via the media or by setting up a clock to “count down” to the Millennium, or making clothes or other items that commemorate the occasion, or printing greeting cards or stationery marking this occasion, or offering special discounts or prizes on these occasions, or holding sporting events or producing special logos for them etc. 

Based on this, it is not permissible for you to participate in making anything that has to do with the festivals of the kuffaar; you should leave this job for the sake of Allaah, and Allaah will compensate you with something better than it in sha Allaah. 

And Allaah knows best.