What did ancient Greeks believe came after death?
You went to Hades which was like a piece of blotting paper – the shades of dead humans moping around doing nothing. Unless of course you were an initiate of a mystery cult, in which your personal engagement with the god of the cult gained you the keys to an afterlife. Early mystery cults were at Dordona, Samothrace, Eleusis to name a few. They were expensive to travel to and pay the fees. Later mystery cults such as Mithraism, Christianity and Isis were free and moved to the potential customers, and so became very popular and spread around the Greek world, then the Mediterranean and further afield.