Related to this question.
Now look at a slightly different case.
Take the example of my grandma in China. She was from the era where people wholehearted support the communist regime. Throughout her life, what she had access to was Marxist ideology about materialism, to which she adhere to. Religion has always been mis-portrayed and shined negative lights on.
Now according to some, she did not receive a just representation of Islam, less so 'clear evidence'. But now suppose I tell her about Islam, and be as just as I can, it is almost certain she will not believe. Because she has this 80 years mindset, and it is as impossible as if you want to convert a pious old age Muslim to atheism!
Therefore, according to some she will be responsible for her denying the sign.
But my question is
Take an arbitrary pious Muslim born in a Muslim family in a Muslim country. Suppose he instead lived a life of my grandma of 80 years of atheism propaganda, after which we tell him about Islam. It is very unlikely that he changes his mind. Doesn't this show a strong disadvantage toward those who were born in such a society (like my family and I)? If you really think about how a Chinese is brought up, there is great chance that he/she will not submit to God due to his family, childhood, education, propaganda from the government and the atheist society. How do I understand it in contrast to the fact that Allah is the Just?
There is Muslim minority in China, but they only dwell in a (few) specific province(s). Except for those born in a Muslim family, there are hadly any people out of 1.3 billion who adopt/convert to Islam.