How should a Muslim deal with requests to print non-Islamic materials in a commercial printing press, such as printing topics for a Christian?

It is not permissible for a Muslim to print, publish, or assist in anything that opposes, contradicts, or goes against the religion of Islam, whether in creed or law. This is based on the Almighty’s saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." If Allah has forbidden something, He has also forbidden its price and assistance in it. Whatever is not forbidden, there is no harm in doing it, selling it, buying it, assisting in it, and dealing with it, whether with Muslims or others, as the basic principle in contracts and transactions is permissibility.