Do you know the story of the Minotaur or Medusa? Or of the great hero Perseus? If you do (or if you don't), you should read the series "Percy Jackson and the Olympians". These books were written by Rick Riordan, The Storyteller Of The Gods.
Percy Jackson is a twelve year old boy with more problems than just school. Since he is a son of Poseidon, the god of the sea, meaning he is more prone to monster attacks and the gods getting in his way.
The big three are Zeus, Poseidon, and Hades. According to popular belief, it is a very well written series. This series tells more about Ancient Greece, the religion in practice, and the lives of many of the characters.
I believe that there had to be something that started all the beliefs, so there may have been gods and goddesses. I definitely don’t know if there are still gods and goddesses in our time, but they did have a big impact on the Greek civilization.
The gods and goddesses go where the flame is the strongest, so in the books the gods are in America. In the series Percy is called on a series of quests. He goes on most of his quests with Annabeth, and Grover. Annabeth is also a demigod, daughter of Athena. Grover is a satyr and Percy’s best friend.
The three of them are trying to save the world from an evil so terrible that even the gods fear them. (My opinion may be different from yours, but I hope they keep making the books and a third movie with way more accuracy than the first two.)
Rick Riordan has written lots of jaw dropping books on Greek, Egyptian, Roman, and Norse Mythology. This is a great series that will definitely leave you wanting more.