I think the distinction can be useful, but we need to be careful about what we mean by “position” and “condition.” By position, we should mean what is actually true of us in Christ. By condition, we can mean the present, imperfect state of our growth in holiness. But these are not two disconnected realities, as though God regards us one way while we remain unchanged. We are united to a living Savior, and both our justification and our sanctification are benefits we receive in Him (WLC 69).
We also need to distinguish two questions. On what basis does God accept me as righteous? Christ’s righteousness imputed to me and received by faith, not the progress I have made in overcoming sin. Has God also begun to change me? Yes. The Spirit really renews those whom God justifies. Justification and sanctification are distinct, but we must not separate them. The Larger Catechism makes that distinction particularly well in Q. 77.
That is why I would not reduce Romans 6 to God’s regarding us as righteous while we continue to struggle with sin. Paul is also explaining that our relationship to sin has changed. Our old man was crucified with Christ so that we would no longer be enslaved to sin. This does not mean that every sinful desire has disappeared. It means that sin is no longer our master.
The command not to let sin reign, then, does not contradict our having died to sin. It follows from it. Paul’s reasoning is that, because we belong to Christ, we must not give ourselves back to the service of sin. Similarly, reckoning ourselves dead to sin is not pretending that we have no temptations. It is believing what God says about our relationship to Christ and acting accordingly. The distinction is between sin’s remaining presence and its dominion over us.
WCF 13 is especially helpful here. It says that “the dominion of the whole body of sin is destroyed,” while our sinful desires are progressively weakened and mortified. It also acknowledges that remaining corruption can prevail against us for a time. We should therefore qualify the idea that sin’s control simply lessens as we mature. Its dominion has been broken; the remaining corruption must still be fought. That fight is real, and progress is not an uninterrupted series of victories.
Colossians 3 puts these things together very plainly. Paul tells believers that they have died and that their life is hidden with Christ in God. He then commands them to put their sins to death. He does not tell them to overcome their sins so that they can obtain a life in Christ. Their life in Christ is the reason they must, and can, begin putting those sins away (Col. 3:3–5).
Pastorally, that matters a great deal. When you discover more sin in yourself than you realized was there, you do not need to conclude that your life in Christ is unreal. Neither should you shrug and treat the sin as something that belongs to your “condition” and therefore does not matter. Bring it to the Savior to whom you belong. Confess it, seek His help, and use the means He has given you. You are not left to improve your condition by yourself while Christ merely guarantees your position. The same Christ whose righteousness is your acceptance before God supplies His Spirit for the battle.