One world one God

Human beings are still an uncivilised creature,barbarian ...one can say.We still speak diffrent languages,still worship diffrent gods,still believe in diffrent nations,have diffrent currencies,......and such things making the rift wider .
I imagine a world where there is only one ruler or organisation to rule the world.Where there is only one language is spoken,where there is only one currency....and where is only one God.