It is a summary of the Islamic rules regarding non- Muslims according to the tow grand Ayatollah Sistani.
Grand Ayatollah Sayyid Ali Hosseini Sistani:
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 the 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 known 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. However, 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. [1]
Notes:
[1] Islamic laws, Grand Ayatollah Sayyid Ali Hosseini Sistani, p. 30.