All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.

It is permissible for Muslim workers to engage in the construction and preparation of cemeteries for non-Muslims — whether Christians living in our countries or others — since this is an act of birr (righteousness) and good conduct. The original ruling regarding dealings with non-Muslims is that they should be based on justice and kindness toward them, and free from any harm or mistreatment. Allah, the Exalted, says (what means): "Allah does not forbid you from those who do not fight you because of religion and do not expel you from your homes — from being righteous toward them and acting justly toward them. Indeed, Allah loves those who act justly" [al-Mumtaḥanah/8]. This is among the rights owed by Muslims to the People of the Covenant, and it reflects the honor that Allah, Glorified and Exalted is He, has bestowed upon humanity in general. Allah, the Exalted, says (what means): "And We have certainly honored the children of Adam and carried them on the land and sea and provided for them of the good things and preferred them over much of what We have created, with [definite] preference" [al-Isrā'/70].

It has been established in the Sunnah, in the reports of the early Muslim generations, and in the statements of the scholars of fiqh, that it is permissible for a Muslim to lend a helping hand to non-Muslims — whether for payment, or out of kindness and voluntary service — with regard to matters pertaining to the preservation of human dignity, including their burial after death. It is related in the Sunnah that the Prophet ﷺ instructed ‘Alī ibn Abī Ṭālib to bury his uncle Abū Ṭālib, who had died without having embraced Islam (see Sunan an-Nasā'ī). It is also related, on the authority of Sa‘īd ibn Jubayr, that a Christian man died, leaving behind a Muslim son who did not follow the funeral procession. Ibn ‘Abbās (raḍiyallāhu ‘anhumā) said regarding this: "He should have followed the funeral and buried him, and sought forgiveness for him during his [own] lifetime [i.e., while his father was still alive]." (Related by Ibn Abī Shaybah in his Muṣannaf)

Imam al-Juwaynī (raḥimahullāh) stated that regarding a deceased non-Muslim who has no guardian (walī) from his own religion [to attend to his burial]: "His shrouding (takfīn) and burial become a communal obligation (farḍ kifāyah) upon the Muslims." [Nihāyat al-Maṭlab, Vol.3/P.17] Imam ash-Shirbīnī (raḥimahullāh) said: "The more correct position (al-aṣaḥḥ) is that the shrouding and burial of a dhimmī (a non-Muslim living under the protection of the Islamic state) is obligatory, to be funded from the public treasury (bayt al-māl); and if this is not available, then it falls upon the Muslims [collectively] — this applies when the deceased has no wealth of his own, nor anyone legally obligated to support him, to fulfill his rights." [Mughnī al-Muḥtāj, Vol.2/P.32]

It is likewise recorded in the authoritative books of the Ḥanbalī school, based on what has been transmitted from Imam Aḥmad ibn Ḥanbal, that it is permissible for a Muslim man to dig a grave for the People of the Covenant (ahl adh-dhimmah). Al-Buhūtī al-Ḥanbalī (raḥimahullāh) said: "There is no objection to digging a grave for a dhimmī in exchange for payment." [Kashshāf al-Qinā‘, Vol.3/P.560]

Accordingly: there is no objection to a Muslim working in non-Muslim cemeteries, since nothing in Islamic Sharī‘ah opposes this. Rather, the original principle governing dealings with non-Muslims is that they be based on justice and kindness toward them. And Allah, the Exalted, knows best.