People say we have always believed in gods (as if the persistence of an idea suggested its validity), but that is merely an illusion of language. After all, what does one mean when one whips out the word god? A creator of all that is? A creator of order imposed on pre-existing chaos (Timeus)? The entelenchy to which we strive, the inspiration, the god as Unmoved Mover? An object or subject of worship? An object or subject presumed to exist despite lack of evidence and in the presence of evidence to the contrary?
The word god has been stretched, mangled, abused, and various definitions are juggled and applied at the convenience of the speaker. To say god is a universal concept is a meaningless statement in a dozen different ways.