It is not possible to say that someone is Muslim if they did not utter the Shahaadatayn
Question

                if someone who is born nonmuslim (christian ) he/she is honest and never commits major sins and he/she belives everybbody is right on their own religion but knows nothing about islam nobody told them about it and they die in this stage  so where will they go on the day of judgement
Praise be to Allah.The person whose situation is described in 
          the question cannot be said to be a Muslim even if his attitude and 
          morals were good, because he did not utter the Shahaadatayn and did 
          not believe in Allaah as his Lord, Muhammad as his Prophet and Islam 
          as his religion. The belief that all religions on earth are correct 
          and that their followers are all following the truth is one of the gravest 
          falsehoods and one of the greatest examples of kufr. Allaah says (interpretation 
          of the meaning);
“…Say: 
          ‘Are those who know equal to those who know not?’…” 
[al-Zumar 39:9] 
“And 
          not equal are the blind and those who see; nor are (equal) those who 
          believe (in the Oneness of Allaah   
          Islamic Monotheism), and do righteous good deeds, and those who do evil. 
          Little do you remember! 
[Ghaafir 40:58] 
“Say 
          (O Muhammad): ‘Who is the Lord of the heavens and the earth?’ Say: ‘(It 
          is) Allaah.’ Say: ‘Have you then taken (for worship) Awliyaa’ (protectors) 
          other than Him, such as have no power either for benefit or for harm 
          to themselves?’ Say: ‘Is the blind equal to the one who sees? Or darkness 
          equal to light?’” 
[al-Ra’d 13:16] 
“Say 
          (O Muhammad): ‘Not equal are Al-Khabeeth (all that is evil and 
          bad as regards things, deeds, beliefs, persons and foods) and At-Tayyib 
          (all that is good as regards things, deeds, beliefs, persons and foods)…’” 
          
[al-Maa’idah 5:100] 
          
“Not 
          alike are the blind (disbelievers in Islamic Monotheism) and the seeing 
          (believers in Islamic Monotheism). 
Nor are (alike) 
          darkness (disbelief) and light (belief in Islamic Monotheism). 
Nor are (alike) 
          the shade and the sun’s heat. 
Nor are (alike) 
          the living (i.e., the believers) and the dead (i.e., the disbelievers). 
          Verily, Allaah makes whom He wills to hear, but you cannot make hear 
          those who are in graves” 
[Faatir 35:19-22] 
          
 With regard to the ultimate destiny 
          of the person referred to in the question, and whether he will be excused 
          for his ignorance or not, and what his situation will be on the Day 
          of Resurrection, we believe that his case rests with Allaah. A similar 
          question has already been answered – please refer to Question 
          # 2443And Allaah knows best.