Muslims abuse non-Muslims by calling them
'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 non-Muslims are hurt - they should accept Islam.
If any non-Muslim considers the word ‘Kafir’ i.e.
‘non-Muslim’ as an abuse, he may choose to accept Islam and then we will
stop referring to him as or call him a kafir i.e. a non-Muslim.