Everywhere the Scriptures provide both the declaration of who we are in Christ (indicative) and the command to respond to that particular declaration in a certain way (imperative). For instance, Paul does not simply issue an imperative like, "Stop living with your boyfriend." He says, "How should we who have died to sin live any longer in it?" Paul does not call people to die to sin; he does not invite them to enter into a higher level of abundant life; there are not appeals to become something which the believer is not already. The believer has died, is buried, is raised, is seated with Christ in the heavenlies, and so on. These are not plateaus for victorious Christians who have surrendered all, but realities for every believer regardless of how small one's faith or how weak one's repentance.
Thus, we must stop trying to convert believers into these realities by imperatives: "Do this," "Confess that," "Follow these steps," and so on. Union with Christ ushers us into conversion and conversion ushers us immediately into all of these realities so that, as Sinclair Ferguson writes, "The determining factor of my existence is no longer my past. It is Christ's past" (Christian Spirituality: Five Views, Zondervan, p.57).
For those who speak as though the filling of the Spirit, the gifts of the Spirit, justification, the new birth, and union with Christ are things to be attained by obedience to imperatives, Paul insists, "But of him[God] you are in Christ Jesus, who became for us wisdom from God--and righteousness and sanctification and redemption--that, as it is written, 'He who glories, let him glory in the Lord'" (1 Cor.1:30-31).
Union with Christ by Michael Horton, Ph.D.