For example, our memory verse a couple of weeks ago:
"Before me no God was formed,
nor will there be one after me.
I, even I, am the Lord,
and apart from me there is no saviour."
(Isaiah 43v10-11... and I know: you're all humming it to that cowboy tune now!)
Or how about this:
"I am God, and there is no other;
I am God, and there is none like me.
I make known the end from the beginning,
from ancient times, what is still to come.
I say: My purpose will stand,
and I will do all that I please."
The answer is: No-one created God. That's what sets him apart from everything else, and all other so-called gods. He has always been, and always will be. And if that hurts your head, so it should! - God is that big.
That is why we have to take him super-seriously. There is no higher authority that we can appeal to on the day God judges us. He is the ultimate one. Therefore when his voice shouts out from the sky over Jesus, "This is my Son, whom I love. Listen to him!" (Mark 9v7) ... we had better do so. Listen to what he says about the one way to be rescued from the judgement we deserve from God; listen to why Jesus said he had to die on the cross and rise again (Mark 10v45).