Is it permissible to translate a book that contains beliefs of kufr?
My question is:
Is it permissible for me to translate this book, seeing that I will only be translating it and receiving payment for doing that?.
Working in translation is basically permissible, and indeed there may be some important jobs which it is recommended to do and to meet the ummah’s need for them. But talking about the translation of a specific book depends on what this book contains. If the book contains innovations, misguidance, immorality or kufr, then the translator of this book has a share in the sin of its author, printer and publisher. But if the book contains scientific or Islamic or permissible material, then there is nothing wrong with translating it.
In our early Islamic history, the translation of the books of followers of idolatrous religions and heretical philosophy had a far reaching effect in causing numerous groups of people to go astray from the guidance of the Qur'aan and Sunnah. This translation began during the year of the ‘Abbasid caliph al-Ma’moon.
Al-Maqreezi (may Allah have mercy on him) said:
Because of al-Ma’moon’s introduction of the books of philosophy, the philosophical schools of thought became widespread among the people and the views of various sects, such as the Qadaris, Jahamis, Mu‘tazilah, Ash‘aris, Karaamis, Khawaarij, Raafidis, Qaraamitah and Baatinis became so widespread that they filled the earth; there was no group among them that did not look at philosophy and choose one of its paths to follow. The trials and tribulations in religion that were brought upon Islam and its people because of philosophy are indescribable.
Al-Khutat al-Maqreeziyyah, 2/358
Based on that, it is not permissible for you to work in publishing the book mentioned in the question, because publishing it implies approval of beliefs of kufr and taking part in propagating them, and Islam warns against cooperating in that which is less serious than that, namely sin in general terms. Allah says (interpretation of the meaning):
“but do not help one another in sin and transgression”
It should be noted that the ruling we have mentioned applies if you are translating something to be published and distributed among the people. But if you are translating that book -- or even something that contains worse kufr -- for a Muslim researcher or a study centre so that these researchers can study the books of these kuffaar in order to refute them and explain why they are misguided, then there is nothing wrong with translating those books, so long as those researchers are trustworthy and you are confident that they will not publish what you have translated for them.
You could play a part in spreading Islam by translating good Islamic books so that they may be published far and wide. You could also translate books that contain scientific or medical information from other languages into Arabic.
And Allah knows best.