It is not possible to say that someone is Muslim if they did not utter the Shahaadatayn
Praise be to Allaah.
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?’…”
“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!
“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?’”
“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)…’”
“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”
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.