[Edited to make it more understandable question]
What if all nation use only a one currency or one global currency?, What will happen to our world?, What is the effect of every nation's or every country economy?, It can make people's unite each other?Any opinion.

this idea might be disastrous to the community, it will be the root cause of greed and poverty. the rich will become more rich and the poor will be poorer. the class of society will persist, everyone will be power greed and most likely to happen there will be only one government and a leader.
I guess it will also be leading to the end of the world and the rule of wickedness as the Bible makes it clear apart from that I don't know what will happen.