At the heart of the conflict between Heaven and Hell is the notion of Fate and Destiny. All mortals have a Fate, the lowest depths to which they can sink, the greatest selfishness they can reach in their lives. All mortals also have a Destiny, the highest heights to which they can aspire, the greatest selflessness they can achieve in their lives. Mortals who reach their Destiny are sent to Heaven when they die, mortals who reach their Fate are sent to Hell. Those who reach neither(or very rarely, both) are reborn into new lives, given another chance to roll the dice.
This, in some ways, is the essence of the conflict between Heaven and Hell. The initial disagreement that led to the Eden experiment and the Rebellion had to do with whether humans would be more likely to achieve Fate or Destiny left to their own devices and whether that meant they deserved a privileged place in creation. The final tally of souls at the end of creation may prove one side right or wrong, though Heaven doesn’t boast and Hell plays their cards close to the chest.
Part of what complicates this is that these things are hard to sense. Angels of Yves can sense someone’s Destiny, but not someone’s Fate. Demons of Kronos can sense someone’s Fate, but not someone’s Destiny. It can be hard to know in a chaotic world what will move someone towards one or another.