One-Punch Man was already full of insane moments, such as Saitama being punched to the moon then jumping back and clouds being split across the entire planet. However, these feats were eclipsed in terms of insanity when a monster stood on top of the moon, so tall that they could be seen clearly from Earth.
The strange fleshy humanoid entity seems to have been working in the shadows, giving powers to various individuals and monsters. Along with power bestowal, they seem to have the abilities of telepathy and mind control. Who are they and what is their plan?
God was first seen in a flashback by Homeless Emperor, where he recounts that the strange being appeared before him in a park. Homeless Emperor believed that humans are fools and a stain on what is otherwise a beautiful planet. God seems to agree with this ideology, because they granted Emperor their powers and then left. They would later do the same thing to Psykos, appearing to her as a large mass of brain cells that resembled the surface of Jupiter. It is unclear why God is giving out these powers; they could be creating an army, but they were very quick to take Homeless Emperor's powers when he was caught by Zombieman.
Perhaps they are interested in causing chaos and destruction and are using these individuals to do just that. Both Zombieman and Pyskos have wreaked havoc on humanity through the Monster Association. God even tried to make a deal with Tatsumaki, appearing before her as Blast in his old outfit. She of course saw through the facade, but an evil Tatsumaki would be a near unstoppable force. She is already a powerful esper, so any enhancement to those abilities would make her possibly the strongest being alive aside from Saitama and God.
Speaking of Blast, the number-one hero seems to know a lot more about God than anyone else. Blast has been going around collecting the strange cubes that God has been communicating through, keeping their influence at bay. Rather than calling them God, Blast refers to the being as 'him.' This could mean Blast knows God's true identity. Blast is a hero who is rarely seen, even by other S-Class heroes. It's possible that his absence is because he is constantly fighting off God's influence on Earth, or perhaps even in space. Aliens do exist in this universe, as seen when Boros invaded, and Blast mentioned that he fights with others against God. Maybe Blast's powers are of alien origin and he fights with a group of intergalactic heroes to stop the influence of God.
Although Garou seems to be the main antagonist for Saitama at the moment, it's clear that God will soon become his opponent. The strange monster is losing many of the pawns he created in the Monster Association, so it seems likely that they will make a new play very soon.