Calling Jews / Christians As Infidels (Kafir) In Quran
Kafir is a terms which means the one who deliberately denies a truth after he has realised that it is the truth. Only God knows the intentions and only He can declare someone kafir. God did call Bank Israel Kafir in His book. These were the ones who were addressed by the Rasool and they denied him, after Itmam e Hujjat, that is thr truth was communicated to them completely and decisively. We on the other hand cannot call anyone kafri now as we do not know the denier deliberately denies or he is not convinced or has some misunderstanding. We call them non Muslim.