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 ritually slaughtered Halal. As for those of non-Muslims who are not from the People of the Book, they are ritually impure (obligatory precaution) and their food is Najis, if it has been touched with a wet hand by them.