The meanings of â€œinfidelâ€ may answer your question: Merriam Webster:
1 : one who is not a Christian or who opposes Christianity.
2 a : an unbeliever with respect to a particular religionÂ b : one who acknowledges no religious beliefÂ
3 : a disbeliever in something specified or understood
Concise Oxford English Dictionary: “person who has no religion or whose religion is not that of the majority. ” Â
So Muslims can call people of other religions as infidels since they are “unbeliever with respect to” this particular religion. Further, Kofr in the noble Qurâan is used in different meanings, some of which are as follows:
- Those who donât believe in God at all.
- Those who donât believe in His messengers.
- Those who are idol worshiper or polytheists.
- The unbelievers with respect to the Prophet Mohammad (s).
The followers of the other religions are called infidel according to the fourth meaning, because they were supposed to acknowledge the Prophet Mohammad’s (s)Â prophethood. Â But in many verses, they are called as the believers in God. For example,
â€œAmong the People of the Book is an upright nation; they recite Allah’s signs in the watches of the night and prostrate * They have faith in Allah and the Last Day, and bid what is right and forbid what is wrong, and are active in performing good deeds. They are among the righteous.â€ (3: 113-114)
â€œDo not dispute with the People of the Book except in a manner which is best, barring such of them as are wrongdoers, and say, “We believe in that which has been sent down to us and has been sent down to you; our God and your God is one and the same, and to Him do we submit”.â€ (29:46)