“And that no man might buy or sell, save he that had the mark, or the name of the beast, or the number of his name.” – Revelation 13:17
I once got a comment from someone who said that the Mark of the Beast mentioned in the Book of Revelation is a microchip. At that time I thought that was the case. However, recently the Lord showed me the error of that thinking. Here’s a very helpful article on the Mark of the Beast.