Is it permissible to translate a book that contains beliefs of kufr?
Question

                I am a translator from English to Arabic and vice versa. Recently I received a project to translate part of the book entitled “Jesus in the Sources of the Church’s Gospels,” written, of course, by a non-Arab author. This book speaks about Jesus the Messiah and how his story is narrated in the various Gospels and how the Gospels vary from one another. The book is not free of discussion about the Messiah as being the saviour and redeemer, and it speaks of Jesus being crucified and then resurrected, etc. You know what is contained in such books that talk about Christianity. 

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?.
Praise be to Allah.
      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”

    [al-Maa’idah 5:2]

    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.