Najis Sharia Laws: Biggotry Towards Jews, Christians, and Infidels
"107. An infidel i.e. a person who denies Allah or the Day of judgement, or associates anyone else with Allah, is impure. Similarly Ghulat (i.e. those who believe one of the holy twelve Imams to be God or say that God has penetrated into him) and khawarij and Nawasib (i.e. those who are enemies of the holy Imams) are also impure. And similar is the case with one who denies Prophethood or one of the necessities of religion i,e. a thing like prayers, and fasting, which are considered by the Muslims to be a part of the religion of Islam when he knows at thing is a necessity of religion. As regards the people of the Book (i.e. the Jews and the Christians) who do not accept the Prophethood of the last of the Prophet Muhammad bin Abdullah (Peace be upon him and his progeny), they, too, are impure according to well-known narrations and this remark is as a precautionary measure. Hence, it is necessary to avoid them also.
108. The entire body of an infidel and even his hair and nails and all liquid substances of his body are impure.
This is quite a difficult ruling in the sense that when one socially interacts in a non-muslim country, one will be shaking hands with non-muslims or accidentally brushing against a non-muslim friend's arm, as an example. What does it mean that they are impure: Does it mean I also become impure and must perform wudhu again? Or does it mean if they are wet and they touch me I become impure and must perform wudhu again? If they are impure and they touch something, then that touched object becomes impure right (they may need to be wet to transfer the impurity as previously mentioned)?"