simultaneously claiming that there is no God?
The universe could not create itself out of nothing, of course.
The alternative posited by some, would be a universe that just always existed. But given the laws of thermodynamics a perpetual motion machine cannot exist other than in a perfect vacuum... and heat will always go from hot objects to cooler objects until equilibrium is reached and all objects are the same temperature.
If the universe always existed there would necessarily be an infinite amount of time behind us. It has no beginning after all.
If there is an infinite amount of time behind us then the universe would have run out of energy by now and everything would be in a state of equilibrium, the sun and stars and planets, asteroids, comets, space dust and whatever else is in the universe would all be one, constant temperature by now.
There must necessarily be someone or something outside of the universe that created it & put it into motion.
The earth is currently spinning at almost 1,000 mph, while orbiting the sun at 66,000 mph, and the solar system is orbiting our "standard of rest" within the galaxy at about 43,000 mph, and that subset of our galaxy is orbiting the galaxy at about 483,000 mph & altogether we are traveling at approximately 1.3 million mph!
https://astrosociety.org/edu/publications/tnl/71/howfast.html#2
We could not do that perpetually.