Romans 3:8

‘And why not (as we are slanderously reported, and as some affirm that we say), “Let us do evil, that good may come?” whose condemnation is just.'

Paul now makes clear that he has had enough of such nonsense. Why not, he asks, then say ‘Let us do evil that good may come?' something that was self-evidently wrong. The condemnation of anyone who spoke like that or acted like that could only be right. We learn here also that people were actually claiming that that was what Paul taught. Paul does not argue about that. He simply commits such a false claim to God. (But we can see how his teaching that salvation was through the grace of God, and through benefiting from the righteousness of Another, so that God was able to declare as righteous the ungodly, could have been twisted to give this significance, false though it would be).