What exactly s the religion? Like, if there's god's, there's a religion. What's the Greek one called? Greek?

The Greek myth religion is specificity called Hellenc, Hellenism, ect. (Yes, it is named after the greek women
Hellen of Troy).

I don't think there was a name back then, since it's one of the first religions. It's simply called Greek mythology now...
However, worshipping gods (Greek, Roman, Egyptian, etc) back then was generally called idolatry. u can look it up to find the exact meaning.