What is the Overall Theme and Key Message of Toaru?

I’m sure this has been discussed before, but I find it more informative and easier to ask people this directly.

This series discusses a lot of different themes and messages. But it’s always different for each volume that it’s hard to keep track of what the key message is and what the whole point of it all is. Even as a novel reader I have a hard time coming to that conclusion (still on NT21 so bear with me). I always just believed that Kamachi wrote this cause he thought it was cool. And that’s probably the reason why.

So I’d like to hear what the community has to say, even if it has probably been asked before.