non muslims unreached by the message of Islam do not automatically go to hell; they are put to a further test on the day of judgement and the outcome of that test determines wether they are saved on not; the hadiths on this indicates that those who would have converted to Islam on receiving a proper message of Islam would pass the test and those who wouldn't have, would fail:
the Prophet said, upon him blessings and peace: Four will present excuses on the Day of Resurrection: The deaf one, the idiot, the senile old man, and the one who died in Fatra (the time between Prophets). The first will say, I didn't hear anything; the second, Islam came and street-children were throwing dung at me; the third, Islam came and I did not have my wits about me, and the fourth: my Lord, no Messenger came to me. Allah will Himself take their covenant to obey Him. They will be told to enter the fire (as a test). Those who obey will find it cool and safe, while those who refuse will be dragged to it. (Aswad, Abu Hurayra)
Al-Bazzar and al-Tirmidhi who graded it hasan narrated that the Prophet said, upon him blessings and peace: The one who died in Fatra, the retard, and the infant will say respectively: No Book or Messenger reached me; You gave me no mind wherewith to understand good or evil; I did not have a chance to do anything. A fire will be presented to them and they will be told to enter it. Those who would have done well in life will obey and enter it (temporarily) while those who would have disobeyed in life will refuse. Allah will tell them: You disobey Me (seeing Me), so how could you obey My Messengers in My absence? (Abu Sa`id al-Khudri)
Al-Bazzar and Abu Ya`la narrated tha same as b) with the addition of the senile old man. Those who obey and enter the fire will go across it speedily. (Anas)
`Abd al-Razzaq, Ibn Jarir, Ibn al-Mundhir, Ibn Hatim, with an authentic chain that meets the criteria of al-Bukhari and Muslim: The Prophet said, upon him blessings and peace: The one who died in Fatra, the idiot, the deaf, the mute, and the senile will be sent a messenger (at that time) who will say: Enter the fire. They will argue and say: How can it be when no messenger reached us? But woe to them! If they had entered it they would have found it cool and safe. Whoever accepts and obeys will enter it. Abu Hurayra added: Read, We never punish until We send a messenger? (17:15).
Al-Bazzar and al-Hakim, who graded it sahih by the criteria of Bukhari and Muslim narrated that the Prophet said, upon him blessings and peace: The people of Jahiliyya will come on the Day of Judgment carrying their idols on their backs. Allah will question them and they will say: Our Lord, You did not send us a Messenger and nothing from You reached us. If you had sent us one, we would have been your most obedient servants. Allah will say: Shall I test your obedience? And He will tell them to enter the fire and stay in it. They will enter it and return again, in fear of its fury and exhalations, and they will say: Our Lord, protect us from it. He will say: Didn't you promise to obey Me if I ordered you something? They will pledge again and enter it, only to come back and plead again. The Prophet said: Had they stayed in it the first time, they would have found it cool and safe. (Thawban)
Al-Tabarani and Abu Nu`aym narrated that the Prophet said, upon him blessings and peace: The retard will come on the Day of Judgment together with the one who died in fatra and the infant etc. (same as(e)) They will keep coming back although the fire would not have hurt them, and Allah will say: I knew your actions from afore, so take them (O Fire).
thus only those non muslims who have been reached by the message of Islam, and thereafter rejected it will be guilty of the crime of desbelief
thats fair isn't it?