السلام عليكم و رحمة الله و بركاته
Many times I hear people say that those who the truth (Islam) came to but rejected it are the only 'kuffar' but those who never heard of Islam do not fall into that category (and they also then claim that that there are very few true kuffar today in the world). Whereas my understanding is that all of those who are not following Islam (whether they heard of it or not) get categorized as kuffar.
So the question is - what is the correct view and also, what is the proof (if any) that all non-Muslims are not kuffar? Did Allah سبحانه و تعالى or His Messenger صلى الله عليه وسلم distinguish between the two kinds of people (and if so, where)?