Romans 3:5-8 :

But if our unrighteousness commends the righteousness of God, what will we say? Is God unrighteous who inflicts wrath? I speak like men do. May it never be! For then how will God judge the world? For if the truth of God through my lie abounded to his glory, why am I also still judged as a sinner? Why not (as we are slanderously reported, and as some affirm that we say), “Let us do evil, that good may come?” Those who say so are justly condemned.

This may seem a bit hard to understand using this free English translation, but it is basically saying this: our sin demonstrates God’s glory because it shows off how merciful He is to us. Our sin makes His perfection look amazing in comparison. So some claim that if this is the case, why would God accuse the sinner since it makes Him look so good? Some people even slandered Paul and other Christian teachers saying that that is what they were teaching.

Paul says clearly here that this is not a Christian teaching and that anyone who tries to promote this kind of teaching is not only wrong but that they will be condemned by God and that it will be “justly” deserved.

God cannot allow any sin to go unpunished and any human who doesn’t change their mind about their sin by admitting that it is bad and accepting God’s only way out of punishment, will be punished and deserve it. If God didn’t punish sin, He would no longer be righteous. This human argument against Christianity, like all others I have seen, is illogical and self-refuting.