Paul is putting these words in the mouth of the imaginary Jewish person he is talking to. AT: "Because our unrighteousness shows that God is righteous, I have a question:"
Paul uses this rhetorical question to show that the arguments against the Christian gospel are ridiculous, since all Jews believe that God can and will judge all people. AT: "And we all know that God will in fact judge the world!" (See: [[rc://en/ta/man/translate/figs-rquestion]])