I've only seen the English dub of Code Geass and this scene is from it.
We learn later on that in the end, Charles was not evil and he was trying to create a better world just like Lelouch. So, when Lelouch did something truly evil in the anime at some point (I think it was when that ship full of material exploded and took their allies out with it), he said
Yes, you're worthy of being called my child now!
Why does Charles say that since he's not truly evil?