God’s righteousness is essentially his unswerving allegiance to his own name and his own glory. God is righteous to the degree that he upholds and displays the honor of his name. He is righteous when he values most what is most valuable, and what is most valuable is his own glory. Therefore God’s justice, his righteousness, consists most fundamentally in doing what is consistent with the esteem and demonstration of his name, his glory. God would be unrighteous if he did not uphold and display his glory as infinitely valuable.
That righteousness to uphold and defend and honor His name and person as the most glorious treasure also necessitates the judgment of God — that is, His judgment of sin and unrighteousness (or "undelight" in Him — treasuring other possessions or people above Him) is right for Him.
So He pours out His wrath on unbelieving people.
And He pours out His wrath on Christ so that all who believe in Christ are spared His wrath and given His righteousness.
Do not miss this: there is now no condemnation for those who are in Christ Jesus (Rom. 8:1). No condemnation. No disparaging looks. No regrets for His saving work. No further judgment. The lexicon for the Greek New Testament says that the word condemnation "does not denote merely a pronouncement of guilt, but the adjudication of punishment." This is Paul's very point in Rom. 8 — there is no longer any punishment to be passed down by the Judge. Judgment is done. We are free.
This is why we can say in response to the Biblical truth of the gospel — be joyful!
In one of my illustrations Sunday morning, I made passing reference to the number of believers now in China. Later in the day, I picked up my latest copy of Christian History & Biography and found that the entire issue was devoted to China and the influence of Christianity in that country, particularly over the past 100 years. I am a long way from finishing it, but it looks to be very interesting (at the moment, none of the articles are yet posted online, but over the next few weeks, they will post them).