Yeah, I'm aware that it's hard to explain morality in natural terms. I've written about that elsewhere, and it's not a problem for this article since the topic here is the Catholic Catechism.

https://medium.com/grim-tidings/no-nihilists-morality-isnt-vacuous-in-nature-663088dd3e01?sk=57e2093d62a4735f8af5ba00f860263a