You didn't read too much about religion, did you?

This subject can be found all over the Internet, besides religious books, but to answer to your question, the Bible states the following:

1. Regarding a single currency
Revelation 13:16–17: "Also it causes all, both small and great, both rich and poor, both free and slave, to be marked on the right hand or the forehead, so that no one can buy or sell unless he has the mark, that is, the name of the beast or the number of its name".

Of course, it is not written exactly that that there will be one single currency, but this is the meaning. The respective mark could be, for example, a NFC chip inserted under the skin.

2. Regarding a single leader
Revelation 13:3–4: "[...]And they worshiped the dragon, for he had given his authority to the beast, and they worshiped the beast, saying, “Who is like the beast, and who can fight against it?""
Revelation 13:7–8: "[...]And authority was given it over every tribe and people and language and nation, and all who dwell on earth will worship it, everyone whose name has not been written before the foundation of the world in the book of life of the Lamb who was slain".

Obviously, nor in this case is written precisely that there will be an unique world leader. But you can understand the meaning. Now coming back to my previous reply, in case cryptocurreny would be that one single currency used when the Antichrist will come, then the Antichrist could be as well the Singularity.