If you mean an omnipotent, omniscient creator, then no, Saitama cannot defeat him.
Saitama is by far the strongest character in the series. From the very first episode, it has been established that no entity can match Saitama's power.
Saitama Beats God and Destroys the Universe.
Goku is an extraterrestrial being who has to lose a fight in order to get stronger. Saitama is a man that can defeat any foe with a single punch. If the two of them were to face off in a one-on-one battle, Saitama would easily win.
According to the fanmade manga God is pretty damn powerful. He literally kicked Saitama to Earth's core. Saitama punched that dude to a different planet all the way from Earth.
Unparalleled Strength: Saitama possesses seemingly limitless physical strength and is capable of effortlessly defeating powerful monsters and villains with a single, casual punch (although this strength is not limited to punches). His punches are so powerful that many monsters simply explode when struck.
Saitama (1000 IQ) VS 1.000. 000 Colossal Titans: 1.000 IQ, 100 IQ, 10 IQ!
He exhibits the same strength effortlessly and yet still has more room for growth. At this point, he hasn't ever needed to use his full power, whereas Goku frequently needs to reach his limits. All in all, Saitama wins this competition.
Goku. Goku is the main protagonist of the Dragon Ball franchise. His abilities include super strength, utilization of ki, teleportation, super speed, and durability. However, he is the strongest anime character because he overcomes adversity and thrives on improvement.
There's literally nothing Saitama can do against Ryuk, the god of death. As he cannot touch him, he cannot use his signature move, Serious Punch, against Ryuk. Once Saitama's name is written in the notebook, he is gone.
God finally appeared to Saitama, the S-Class hero Flashy Flash and the monster Oculette, when they touched a strange, cube-shaped object, and were able to hear God's voice in their heads. He offered them to make a "fervent wish", to see if they were "worthy vessels to bestow my power upon".
The origin of Saitama's immeasurable power remains mysterious and unclear. Although he tells everyone he got his incredible power through mere physical training, no one believes him at all.
God is the overarching antagonist of the Monster Association arc in the manga One Punch Man and possibly the entire series. It is a mysterious entity that desires the eradication of all humanity. However, it chooses to remain hidden for the time being and instead grants powers to others who share its thoughts.
That is, God's height is approximately 84% of the Moon's diameter. If the Moon in the One Punch Man universe has the same dimension as the Moon in our universe, that is, considering it a perfect sphere 3,474.8 km in diameter, we have that the height of God is approximately 2,921.4 km.
Either that, or there could be a far more potent threat from a different dimension which would be explored later by the mangaka. That being said, it is unlikely that Saitama would lose a fight owing to his unlimited potential and his perpetual growth.
If we calculate this distance over time, Saitama speed comes up at 150 9236 miles per second, which is quite close to the speed of light. It's safe to assume that he merely jumped. with no charging up, which means he can be faster. In short, Saitama can travel at the speed of light.
Can Saitama fly? Like everyone else is saying, he can just jump really high and move fast. He has no flying powers.
Saitama has clearly demonstrated that he possesses some semblance of intelligence, yet it doesn't negate the fact that he clearly isn't the sharpest tool in the shed. Saitama's lack of intelligence could very well become one of his biggest weaknesses, with villains only requiring wits to outsmart the famed hero.
Now, readers learned that not only Saitama is capable of suffering, but he is also afraid of completely losing his humanity, and this is why he kept close to friends like Genos, King, and even Bang, despite his apparent annoyance towards them.
Saitama has never been shown to be sick or even affected by sickness.
Saitama vs cat
[ Still trying to do the math on how, the only thing to ever actually damage Saitama in the series is a cat scratching his face.
It is true that we have not seen Saitama's full power, and his fight with the God of his universe is fast approaching, but until we see him at his full potential, it is clear that Saitama is no match for Zeno now.