Metaphysical issues can hardly be proved by exact science.
I would not call it imaginary crap. Some people have ability of remebering their past lives knowing some details that can be confirmed from independent sources. Especially children are outstanding in this regard. And then there are out-of-body experiences..
Those things are neither church invention or figments of people's imagination. Ancient civilizations, our ancestors (Atlantis, Sumer, Egyt, etc.) knew this long ago. They assembled their knowledge for us long before first organised church was established.