In any case, I have to get rid of one misconception you have : I would be greatly surprised if even 1% of humanity ended up in heaven.
Do not underestimate the wickedness of man, and do not forget that not only God knows perfectly every action but also every thought and hidden intent. Under those circuмstances, most people who outwardly act as if they were good would be guilty in the eyes of God.
The reason I brought up North Koreans in gulags is that rejecting the "Supreme leader" (who is worshipped as a god in North Korea) is proof that they have the natural law inside them even if they are not christian they see there is something inherently wrong with this idolatric cult.