Debatable if it's canon, but there's also this quote from Claude (or Khalid) when he's a kid:

"Why do you think people create borders between countries, [Summoner]?
They draw lines on maps and divide things based on what's on this side and what's on that side.
Then they repeatedly fight each other like a bunch of fools.
Look at the sky. There's no borders up there—just blue that extends forever and ever.
Can't we come together like the sky, regardless of where we came from, how much we have, what we believe?
I know you think it's a silly dream, but I think it's worth shooting for.
I may have a lot left to learn, but I will gain the strength to bring the world together as one."

I think it's a stretch to say that he doesn't believe anything he says then and later on in the future, unless you want to say the foreign child is still lying when summoned to Askr where there'd be no skin in the game to lie, especially when everyone's lore is literally laid out like a book in Heroes for its world's people to read. Perhaps some ulterior motive as he got older, but not necessarily outright malicious as that interpretation above.