Is he who dies upon a religion other than Islam, yet the call to it never reached him, considered among the people of Hellfire? And are Muslims sinful for not inviting him to Islam? And who is primarily responsible for that?

Muslims must be callers to the religion of Allah the Almighty, for Allah says: (And who is better in speech than one who invites to Allah and does righteousness and says, "Indeed, I am of the Muslims"). A group from among them must undertake this mission. And whoever the call of Islam reaches and he does not believe in it, then he is among the people of the Fire due to his failure to seek the truth, as the Prophet, peace and blessings be upon him, said: "By Him in Whose Hand my soul is, no one from this nation, neither a Jew nor a Christian, hears of me and then does not believe in me, but he will be among the people of the Fire." The term "my nation" here refers to the 'umma' of invitation (umma al-da'wah).