Najis things » Kafir

107. An infidel i.e. a person who does not believe in Allah and His Oneness, is najis. Similarly, Ghulat who believe in any of the holy twelve Imams as God, or that they are incarnations of God, and Khawarij and Nawasib who express enmity towards th e holy Imams, are also najis. And similar is the case of those who deny Prophethood, or any of the necessary laws of Islam, like, namaz and fasting, which are believed by the Muslims as a part of Islam, and which they also know as such.
As regards the people of the Book (i.e. the Jews and the Christians) who do not accept the Prophethood of Prophet Muhammad bin Abdullah (Peace be upon him and his progeny), they are commonly considered najis, but it is not improbable that they are Pak. Ho wever, it is better to avoid them.

108. The entire body of a Kafir, including his hair and nails, and all liquid substances of his body, are najis.

109. If the parents, paternal grandmother and paternal grandfather of a minor child are all kafir, that child is najis, except when he is intelligent enough, and professes Islam. When, even one person from his parents or grandparents is a Muslim, the child is Pak (The details will be explained in rule 217).

110. A person about whom it is not known whether he is a Muslim or not, and if no signs exist to establish him as a Muslim, he will be considered Pak. But he will not have the privileges of a Muslim, like, he cannot marry a Muslim woman, nor can he be buried in a Muslim cemetery.

111. Any person who abuses any of the twelve holy Imams on account of enmity, is najis.