It depends on our merit when we die as to our reward in Heaven. Everyone shall be perfectly happy. To explain this take 2 cups 1 small and 1 large. Fill them both up and there both full. But the larger one has more water. It is the same with heaven. Some people have a larger cup ( potential for happiness) than other people. But all are full (perfectly happy).
Eg. Blessed Theresa probably has a greater capacity for love and therefore a greater capacity for eternal happiness than a mobster who repented on his deathbed. both are saved and perfectly happy reletive to themselves, but Blessed Theresa is happier objectivly.
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