Ahl-e Kitab(Christians, Jews and Zoroastrians) are ritually pure, but non-Muslims(Infidels) who are not from the People of the Book, they are ritually impure.
Question: What is the difference between Ahl-e Kitab (the People of the Book) and the rest of the unbelievers(Infidels) with respect to Shari'ah law?
Answer: Ahl-e Kitab (Christians, Jews and Zoroastrians) are ritually pure and it is permissible to eat their foods even if we know that they have touched the food with wet hands. Yes, if their food contains meat, it is necessary that the meat should be halal. As for those of non-Muslims(Infidels) who are not from the People of the Book, they are ritually impure and their food is najis, if it has been touched with a wet hand by them.
1. Ayatollah Seyyed Ali Sistani , Question & Answer, Non-Muslims.