The correct form would be written as Greco-Roman.
There was not a Greco-Roman religion. Greco-Roman is a term which refers to art.
Greco means a combined form representing Greek. A common used term is Greco-Roman. Meaning a combined form representing something that is representing Greek and Roman.
Greco-Roman is the term meaning Greek/Roman, for example, things during that time period; or if you wanted to talk about Greco-Roman Mythology (Greek and Roman Mythology) Hope this helps. :)
Bobby Del Greco was born April 7, 1933, in Pittsburgh, PA, USA.
Nikki Greco goes by Nikki Greco.
Aldo Greco has written: 'Aldo Greco'
Barry Greco is 6'.
Betty Greco's birth name is Elizabeth Greco.
Buddy Greco's birth name is Greco, Armando.
Dennis Greco's birth name is Dennis A. Greco.
Sam Greco's birth name is Salvatore Greco.
Valerio Greco goes by Valerio Greco, and Silentvalerio.
Nancy Greco's birth name is Nancy Jeanne Greco.
Nicholas Greco's birth name is Nicolas John Greco.
Pavel Greco's birth name is Emiliano Pavel Greco.
The correct form would be written as Greco-Roman.