Adam: but I'm just a kid...
Aziraphale: but that's not a bad thing to be, Adam. You know, I was scared that you'd be hell incarnate, I hoped you to be heaven incarnate. But you're not either of those things. You're much better. You're human incarnate.
Crowley: Adam, reality will listen to you right now, you can change things.
Aziraphale: and whatever happens, for good or for evil, we are beside you.
For me, the meaning is this: we, humans, from the smallest to the greatest, are capable of changing the world. We can refuse to be what others tell us we are. We can choose our own path. It doesn’t matter whether we are children or adults — everything is in our hands. Our destiny, and therefore the destiny of the world, is in our hands. What we are born as does not define us.
Unfortunately, I don’t know how this line originally looked in English, but in the Russian translation of the book there is a sentence like this:
“It’s just like expecting a tailless mouse to give birth to a tailless baby mouse.”
That is the essence of Good Omens. Those who think they mean nothing and have no influence are deeply mistaken. Every person matters; every voice matters. What we are born as does not determine who we truly are.
The Antichrist, whose purpose at birth was to destroy the planet, humanity, and claim his throne, is an ordinary eleven-year-old boy who rejects his predetermined role because he sees no point in ruling or power, he simply doesn’t need it. All he wants is to enjoy life on Earth, to enjoy playing with his friends, the small earthly joys, imagination, his imperfect but loving and loved parents, to go to school, to play with his dog in the garden, to steal apples from the neighbor’s tree, to grow up and love, to love, and love again this imperfect world.
We can change the world. We can do it by starting with ourselves, by refusing to accept what we are told we are by definition, by default. And it doesn’t matter whether it’s for good or for evil, our Aziraphale and Crowley, faithful (shitty, but still lol) protectors of Earth, humanity, and the small earthly pleasures that we created and that they came to love just as much as they love humanity itself, will always be with us, believing in us.