Why is God not unfair in pouring out His wrath on Christ-rejecters?
God is not unfair because at the cross every human being’s sin debt was paid in full. His wrath on Christ-rejecters is just, since they refuse the payment already made for them. The text asks if God is unrighteous to take vengeance, and the answer is no.
Les teaches that Paul raises the question: if our unrighteousness commends the righteousness of God, what shall we say? Is God unrighteous who takes vengeance? Les explains that God will one day pour out His wrath on Christ-rejecting men, but He is not unfair. The reason is that every human being who has ever lived had his sin debt paid in full at the cross. Therefore, those who reject Christ are rejecting a payment already made, so God's wrath is not unjust.