What is the ruling on eating food with or dealing with someone who was appointed as a teacher based on the recommendation of a communist party?

The treatment of non-Muslims, such as the People of the Book and others, must be subject to Sharia regulations. They should not be taken as friends, based on the Prophet's (peace be upon him) saying: "Do not accompany anyone but a believer, and let no one eat your food except a pious person," because an infidel might draw his companion to his creed. It is not permissible to deal with him in matters known with certainty to be haram; however, what is not known with certainty to be haram is permissible to consume. There is no objection to eating food from a communist teacher if the food's source is his salary, which he receives for teaching, because he receives a salary for a permissible benefit under Sharia, which is teaching.