“Arise, O God, judge the earth; for you shall inherit all the nations!” – Psalm 82:8
This is a lament psalm focusing on injustices. Judging is an act which is done by a ruler. God’s judgment is just. All nations already belong to God and in his pure justice it is desirable to God to be the one doing the judging. The psalm points to the future when the Messiah is seen to inherit the nations. It is Jesus who will rule over all the tribes and nations. How beautiful to know our sinful and unjust world will be inherited by Christ, the perfect judge. Our human leaders fail to implement fairness and therefore our psalmist clamors for righteousness from God’s rule.
This is a request for God to pour out his justice and mercy as he sees fit, to rule in his perfect way. The result will be mercy on the elect and well-deserved justice for the wicked. Christian disciples seek God’s reign because only he is good, maybe not good by worldly standards, but perfectly good and full of grace. David Platt said, “We ask God to judge, and then we anticipate God to come—to come and claim his inheritance. To come and establish a new heaven and a new earth where evil and injustice will be no more … and goodness and justice will reign forever. This is what we do. We plead for God’s justice to reign, and we keep pleading with anticipation in our hearts, because we want God’s kingdom to come.” God will reign over all and bring glory to himself.
Christ can inherit the nations without the help of his elect. However, he has joyfully conscripted his church to train and send broken missionaries to bring the nations to him. Certainly, Jesus does not need missionaries, but he desires, for his own glory, to use his laborers to enter the sinful world and take with them the perfect grace of Christ.
 David Platt, “A Plea for Justice,” in David Platt Sermon Archive (Birmingham, AL: David Platt, 2014), 4395.