You took the verse out of context. Your conclusions are way off.

God is saying that if the ISRAELITES sinned by abandoning God and turning to foreign gods. And after God disciplines them with the sword, or famine, or plague. THEN if the Israelites, which are the only nation that are his people called by this name, if they repent then God will heal their land FROM THE DESTRUCTION THAT GOD HIMSELF CAUSED. So the rest of what you said doesn't apply.