A book says a bush burned and wasn't consumed so, what do you conclude? Well it's in a book and you didn't see it, so first you'd jump to it's made up. But, since lightbulbs also burn without being consumed, it's not totally implausible. And that there's oil in the region, maybe it was just wicking up a pool of petroleum.

It's not about the miracle, it's about the break to crazy that lets you get from the question of whether a bush actually burned or not to there's a God who wants you to say nice things about him in your head and coincidentally hates exactly who you hate and has a torture room for them, but shush, no telling, it happens after they die.