Throughout his ministry, William Branham spread fear through his revival circuits that Christians might accidentally accept the “Mark of the Beast” from the book of Revelation in the Bible. As he rose to the central figure of his cult of personality, he claimed that those who he did not control would be doomed, or more specifically, accept the Mark of the Beast from Revelation. In the doctrine he created, "cold and formal Christians” —those not in agreement with his doctrine, were accepting the “Mark of the Beast”. Yet he described many varying ways in which a person could receive this "Mark of the Beast."

In the early years of the Cold War, Branham claimed that Communism was the Mark of the Beast and that Communism would rule the world. He even claimed that he was arrested for preaching about this. In contrast, the 1954 version of Branham's stage persona rejected the notion of Communism being the Mark of the Beast.

When Branham’s Christian Identity doctrine called "Serpent's Seed" was introduced, Branham claimed that many people had already accepted the Mark of the Beast and were completely unaware. He claimed that there were only two classes of people on the earth: those with the Mark of the Beast and those without. Yet other versions of his Stage Persona disagreed, teaching against his own Serpent’’ Seed doctrine and claiming that the two "marked" or "unmarked" bloodlines did not yet exist; the "Mark of the Beast" designation would occur after his cult had left the earth.

In some versions of his stage persona, Russia was linked to the Mark of the Beast and the End of Days, and in other versions of the stage persona, the Mark of the Beast would come from Rome. In those versions, he predicted that all non-cult Christians would become Roman Catholic which was … ”The Mark of the Beast”.

You can learn this and more on william-branham.org.

Mark of the Beast:
https://william-branham.org/site/research/topics/mark_of_the_beast