The scene above, Gojo comforted Yuji as he knew that he was terrifid seeing jogo raw power. Then after he defeated him he said this statement. In summary, Gojo saying that Jogo was weak was a ploy for Jogo to show his true power and that he said that Yuji and the others must be powerful enough to beat him.

Jogo is one of four cursed spirits born from humanity's collective, subconscious fears. His appearance and abilities imply he was born from their collective fear of volcanic eruptions.