All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
It is not permissible to attend these practices that include aspects of idol-worshiping, let alone participate in them with any kind of participation. Allaah says (what means): {And when you see those who engage in [offensive] discourse concerning Our verses, then turn away from them until they enter into another conversation. And if Satan should cause you to forget, then do not remain after the reminder with the wrongdoing people.} [Quran 6:68]
Based on this, the scholars determined that it is forbidden to attend places where evil is taking place without having a valid purpose, such as denying the act of the doer of evil. Being forced to attend is not a coercion that is Islamically considered. To learn the criteria of valid coercion, please refer to fataawa 196781 and 277117.
Therefore, it is an obligation to quit studying or working in these institutions as long as this is the case, and whoever fears to face an unbearable harm, then he may continue in them provided that he leaves whenever he is able to do so.
It is also not permissible to congratulate them on their festivals, as already stated in fatwa 41447. As regards eating the food which they offer to you, then there is nothing wrong with eating it as long as that food is lawful to eat in Islam, as we have highlighted in fatwa 12267.
Allaah knows best.