Almost all Shiite faqihs agree on the nijasah of the kuffar (non-believers)[1], but the Impurity of Ahlul Kitab (People of the Book) is an issue of dispute amongst them. To further explain this issue, the fatwa regarding the impurity of non-Muslims (kuffars) and the People of the Book originates in verse 28 of Surah al-Tawbah which expressly refers to the impurity of pagans and polytheists considering  their impurity as a reason for preventing them from entering Masjid al-Haram (Grand Mosque).  The narrations transmitted and the reports related in this regard are varied and there are different interpretations about them one of which is the Nijasah or the ritual impurity of all non-Muslims among which are the Ahlul Kitab. This viewpoint was chosen by Ayatollah Golpaygani who stated and thoroughly explained about it in Nehayat al-Afkar fi Nejasah al-Kuffar. Likewise, this was also Imam Khomeini’s verdict on the issue.[2]
Another interpretation is the taharah (purity) of Ahlul Kitab and nijasah of the rest of the non-believers. This verdict has many advocates[3]. A hadith from Imam Reza confirms this fatwa.[4]
A third view is the tahara of all people, perceiving the nijasah of non-Muslims a result of normally making contact with a najis (impure) substance such as pork and wine, thus if they cleanse and wash themselves they will no longer be najis. Therefore, these people aren't najis per se, they become najis as a result of other najis substances.[5] The impurity is accidental, not essential.
Some other scholars, however, believe that the reason for considering non-Muslims as impure is political. This ordinance is aimed at limiting communications between Muslims and non-Muslims, as far as possible. According to them, efforts should be made to prevent Muslims from associating with them as well as curb the influence of their destructive thoughts and ideas on Muslims who have less scientific and ideological capability as compared to them.
As was pointed out, the reason for these different beliefs, views and deductions emanates from the conclusions drawn out from the narrations and exegetical analyses especially those carried out by jurisprudents or legal experts in legal and jurisprudential area.
Hence, in order for a person to get to an answer to this question, he must either be a Mujtahid to carry out an independent research about this subject and finally come to a conclusion therefore, or he should refer to his marja’s fatwa and see what his opinion is on the issue. There is also a third option and that is, he should exercise precaution in this regard. Precaution means that if one is associating with non-Muslims, he should wash his body, clothes or belongings which he uses during prayer or which are required to be clean. He can also change his clothes and wear those which are clean. Obviously, this is a difficult task as it involves hardship but he should keep in mind that a person who performs a difficult job also earns more reward. The harder a duty, the more reward one earns as it is the significations of narrations regarding the most meritorious deeds. [6]

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