It is a common belief that perfect happiness awaits those who go to heaven.
This poses a problem.
It is also a common belief that those who suffer greatly in this life receive a higher reward in heaven.
How can that be? Is perfect happiness perfect, or isn't it? Is Mother Theresa happier than Joe Schmoe who simply did the bare minimum to get into heaven? If she is, then that implies that there is something about Joe Schmoe's existence in heaven that makes him not perfectly happy....which opposes the assumption that Heaven = perfect happiness.
Here's another problem. The thing that made Mother Theresa WHO SHE WAS, was her caring for the sick, poor, orphaned, and dying. This is what fulfilled her and made her happy. So, if there are no sick, dying, poor, or orphaned in heaven, how can she be happy? There is nobody to care for. The essence of who she was can no longer function.
Is she somehow reprogrammed, or stripped of her essence upon entering heaven so she no longer has the desire to help others? If not, then she will forever have an unfulfilled desire, and thus, not perfect happiness.
See, there are many problems with the concept of heaven, that most people don't even consider.
Ponder heaven for a while, and you will see that it is a superficial concept, akin to the fantasies and wishes of a young child.