We have to pause for a moment and consider what we mean by the term ‘disbeliever’. In my opinion, there is only two state of ‘dis-belief’.
The first state I refer to ‘disbelief out of arrogance’, and therefore by choice. One enters in to this state once the truth (in this case the existence of Allah) has been CLEARLY manifested to him, and made absolutely clear with no reason left for him/her to deny/reject it (given the recipients circumstance, and faculties). However, if, after clear evidence/proof, he/she still rejects the truth, it is then that one enters into the state of Kufr.
To better understand this stage, consider the example of pharaoh. After first listening to the message of Allah, communicated through the Prophet Musa, Pharaoh asked him to bring about a miracle. Pharaoh, who trusted in the skills of his magicians, wanted Musa (AS) to confront his magicians, since he was certain of his ultimate victory. In his opinion, a successful confrontation would secure his authority. However, the magician's’ performance was mere sorcery, which the miracle performed by the Prophet Musa rendered void. Thus, Pharaoh was defeated. Yet, instead of acquiescing and accepting to be rightly guided, he became still more arrogant.
“Witnessing the miracle performed by Musa (AS), the magicians embraced faith and came to believe in the Lord of Musa (AS). Nevertheless, their choice had no impact whatsoever on the hardened heart of Pharaoh. Rather, he decided instead to use force: The magicians threw themselves down in prostration. They said, “We believe in the Lord of all the worlds, the Lord of Musa and Harun.” Pharaoh said, “Have you believed in him before I authorised you to do so? This is just some plot you have concocted in the city to drive its people from it. I will cut off your alternate hands and feet and then I will crucify every one of you.”” (Surah Al A’raf 7:120-124)
The second state I refer to as ‘the absence of belief (or disbelief out of ignorance). This state is characterized by one whom the truth (in this case the existence of Allah) has either never reached or has not been clearly manifested to him/her. Again, I don’t consider this state ‘disbelieve’ but rather the ‘absence of belief’; because in such state one either never encountered the truth or has not been clearly manifested to him, hence he/she never had the option to believe or disbelieve.
To illustrate the second stage-absence of belief, consider the following scenario:
Suppose there is a man on an isolated island, and has been on that island since birth. Now suppose that that man has never made contact with anyone or anything outside of that island. As such, said man would have no idea of the existence of a God, as the truth (in this case God’s existence) has never reached him nor been clearly manifested to him (seeing as how he’s on an isolated island); as such, the man would have an ‘absence of belief’ in the existence of a God. Now suppose this man dies on that island, without the truth (in this case the existence of a God) having ever reached him. Now tell me, would it not be unjust of/for Allah to punish him in this scenario? Seeing as how the truth (the existence of Allah) never reached or been clearly manifested to him; hence never having the chance to believe or disbelieve.
Therefore, one whom the truth of a certain matter (in this case the existence of Allah) has either never reached him or been clearly manifested to him (in my opinion) cannot been necessarily considered a ‘disbeliever’. Rather his scenario is one of ‘absence of belief’.