Thanatonauts. The Empire of Angels (set of 2 books)

The legendary duology by Bernard Werber. The set includes 2 books: «Thanatonauts» and «The Empire of Angels».
«Thanatonauts»
Death. The point of no return that causes the living to feel confusion and fear. No one has ever returned from there, and no... one has ever been there as a guest beyond the confines of life. However, with the invention of thanatonautics, everything changes. Several brave souls invented a way to travel along the edge of shadows, which led to unpredictable consequences - after all, every faith wants to prove its righteousness and colonize the afterlife.
«The Empire of Angels»
What is up there? Do all souls go to heaven? Can humanity be saved?
The pioneers of «post-mortem geographical discoveries» Michel Pinson and Raoul Razorbak meet again to continue the epic of the thanatonauts. They will have to practically learn all the nuances of the angelic craft and unravel the obscure heavenly hierarchy. But they would not be true explorers if they stopped there. Where do angels go once they have fulfilled their purpose? Who makes decisions above the angelic world? And what if the answers to these questions are hidden in other galaxies?