Let's jump right to it with a concrete example:
A human being is put in absolute quarantine the very second it is born. During its entire lifespan it will have no interference with anyone or anything apart from its supplied provision. It will never be able to commit a sin apart from its ability to worship itself or to create bonds with deities that are created by him-/herself (which is highly unlikely given its isolation). On the other hand though, it will never be able to commit any "good" actions either as there is no way it could ever care for, or love anyone but itself.
And now the question to ponder: Would this human being go to heaven, as God feel sorry for it and is aware that there was no way it could do anything about its situation, or would it go straight to hell since it completely lack faith in God and never worshipped him in any sort of way? As I see it:
- If it ends up in heaven, we have just found a way of assuring someone a place next to God once they die.
- If it ends up in hell (due to a lack of faith and/or selfless actions), God evidently has no mercy for the unfortunate.
Because those two are the only options, right?
(I'm obviously not religious myself, but those who are should find this question interesting to discuss.)