Actually rational thought would avoid making unfounded assumptions regarding a creator and its properties.
Unless of course you have incredible, previously unknown knowledge to share with man-kind.
I'm not assuming anything.
If our Hypothetical creator Does not have a creator himself, then you still have to find
his origin(which you can't). If he does, then you have to find out what made that creator, and then the question repeats itself ad infinitum, which is insane. It's a simple concept even a child could grasp.
I say creator as opposed to god, because said creator could simply be a couple of Fairies wearing Boots, or the Personification of Bullshit. Or God.
And since the Concept of a superior being who made everything is unfalsifiable, it's more intellecually honest to act as if he doesn't exist.
Now, ignoring any argument that relies on god, Why is the earth flat?