Claiming that the universe is completely natural, and yet somehow created itself or exists eternally, makes no logical sense. How could a natural, material world create itself, or exist outside of time?
However, a supernatural being, which is not matter and thus not constrained to spacetime, can thus exist eternally, outside of time. It does not need to be created because there is no "start" outside of spacetime, it is eternal by definition.
Thus it seems perfectly logical that a supernatural being can exist outside of time and thus be eternal and non-created, but no natural, material realm can.
You know, I always took you for a rational dude.
But this... yikes.
First of all, you're making assumptions here-- no one (scientists) says the universe "created itself"-- that's a strawman. The current position of cosmologists is that the universe has always existed in one form or another, and may be a part of an infinite parallel with other universes.
Second, a supernatural being by definition cannot exist in nature, otherwise, it would be natural. As far as I'm aware, the gods of man interact with men, thereby making them a paradox-- they are no longer supernatural if men can hear them, for example. Their voices can only be heard if there is a medium, such as air. That, by definition, would make them a natural being, hence the paradox.
So no, it's not perfectly logical, most especially because the god of the bible, at least, is described as looking like us, meaning he can be seen, meaning he's not supernatural, meaning none of this makes sense.