>>704150
It boils down to miracles.
If one can pray for intercession to a person who is assumed (but not confirmed) to be in heaven, and a miracle results from it, it can be reasonably assumed that the person is in communion with god in heaven.
>The Catholic and Orthodox churches claim that you cannot know for sure if someone is saved
You cannot know for sure whether you're saved…until you get there. You also cannot know that someone is damned, as there is always the possibility that a person who is not demonstrably in heaven may be in purgatory on his way to heaven.