I know that in the day of judgment those that didn't have any possibility to learn Islam will have a parallel world that will last 50 thousand years created for them and will be tested by being sent a prophet.
Imagine those countless indigenous tribe in the Americas that didn't have any possibility of learning Islam. They had completely different religions from Islam and completely different obligations and prohibitions.
Allah says: To every folk we have given their laws.
Does it mean only Islamic laws or all laws including polytheistic and atheistic laws?
If a polytheist that lived 16 centuries ago in the middle of the jungle faithfully followed the obligations and prohibitions of his religion, will he be rewarded for that?
Are their sins written according to Islamic law or the laws of the polytheistic religion they have?
Certainly a polytheist that disobeys and does grave sins according to his polytheistic religion, like insulting an idol and not respecting obligations of his idolatrous religion, not because he believes in Islam, but because he is arrogant, cannot be the same with a humble idolater. He insults his idolatrous religion out of arrogance and not because he believes Islam.
What can we say about other sins like murder, theft, treachery?
Are they written by the angels according to Islamic law or the polytheistic religion they belonged to? What about those that were atheistic and lived in the middle of the Amazon forest before Columbus discovered America. According to which laws are their sins and good deeds written?