[Romans 6:11-23] is about God’s work of sanctification in believers’ lives – also now – as he causes his church to “grow the growth of God” (Col 2:19). The section is about sanctifying and the key words in it are not the imperatives but the great statements which refer to God’s work:
“You are not under Law but rather under grace” (6:14).
You were delivered to a pattern of doctrine (6:17).
You have been set free (6:18, 22).
“The gracious gift of God is eternal life” (6:23).
Paul’s words about sanctifying do not lay on Christians a post-Gospel dose of (guilt-producing!) Law. “Sanctifying” is Gospel talk. The change of lordship transfers sinful man out of that vicious cycle in which he is trapped when trying to be right with God by doing works of Law.
The reign of grace is none other than ὴ βασιλεία τοῦ θεοῦ, the kingdom of God. The Savior who calls out “Come unto me, ye weary” (Mt 11:28) has given rest: grace, a gift. Grace shines down from heaven in Jesus Christ, and those who are baptized are justified, standing in it (Rom 5:1), walking under it (6:14). It warms, releases, vitalizes them.
It is the prodigal son who is “under grace.” Will his brother, in whom reigns opinio legis, repent and come into the joy of grace (Lk 15:11-32)? The father who is waiting for his sons is giving a feast in the household where grace reigns; reckoning everything in the way of Law is what keeps one from being joined to that household and its eternal joy.
But those who are under grace are not under Law. They spring up, newly alive, and should never again let opinio legis cause them to doubt the good standing (for Christ’s sake) in God’s sight. Under grace, they are delivered into the power and care of the Gospel, the pattern of sound doctrine. This doctrine is not a moral code, but the word of grace, the ministry of the Gospel, the work of Christ (through his representatives) to guard the Christian and keep him in the one true faith – in the Christian church, where Christ richly and daily forgives sins (sanctifies continually) and at the last will raise the dead and give to believers in Christ eternal life. Through the doctrine, through the Gospel, through the ministry which is the continuation of Christ’s ministry, God is sanctifying. And so the Christian person, under grace, kept in the faith, is freed – to serve (Rom 6:18) and to rejoice (Rom 5:11).
Such is the happy life of the one who lets himself be made a slave of the God who justifies the ungodly and graciously gives the gift of eternal life (Rom 6:23).
– Jonathan F. Grothe, The Justification of the Ungodly, Volume 1, pages 354-355