TIL The younger brother of Jesus

Neat. From my understanding his claims haven't been disproven

He came to believe that his celestial father, whom he saw in the visions, was God the Father, his celestial elder brother was Jesus Christ, and he had been directed to rid the world of demon worship.

While convalescing, Hong dreamed of visiting Heaven, where he discovered that he possessed a celestial family distinct from his earthly family, which included a heavenly father, mother, elder brother, sister-in-law, wife, and son.[19] His heavenly father, wearing a black dragon robe and high-brimmed hat with a long golden beard, lamented that men were worshiping demons rather than he himself, and presented Hong with a sword and golden seal with which to slay the demons infesting Heaven.

Hong left Guangzhou on 12 July 1847 to search for Feng Yunshan.[38]Although robbed of all of his possessions, including his demon-slaying sword, by bandits in the town of Meizixun

The family sure gets around: https://en.wikipedia.org/wiki/Kirisuto_no_haka

where does it say 20-30 million people? on the page it says he had 30'000 followers:

By 1850, Hong had between 10,000 and 30,000 followers.