Why do Muslims abuse non-Muslims by calling them Kafirs?
Kafir means one who rejects.
‘Kafir’ is derived from the word ‘kufr’, which means to conceal or to reject. In Islamic terminology, ‘Kafir’ means one who conceals or rejects the truth of Islam and a person who rejects Islam is in English called a ‘non-Muslim’. If a ‘non-Muslim’ considers being called a ‘non-Muslim’ or ‘Kafir’, which are one and the same, an abuse, it is due to his misunderstanding about Islam. He or she needs to reach out to proper sources of understanding Islam and Islamic terminology, and not only will he not feel abused but appreciate Islam in the proper perspective.