Some union advocates donâ€™t like the theological approach of asking what problem a specific doctrine solves (sorry Matt). But since we are in the arena of salvation, which is supposed to be a remedy for sin, inquiries about effects of certain doctrines, whether doctrinal or personal, seems fair.
So as near as I can tell, one of unionâ€™s greatest benefits is that it solves the Roman Catholic charge against Protestants of antinomianism, with added benefit of leaving Lutherans alone to bear the charge. (Why we donâ€™t want to stand by our Lutheran brothers and offer aid and encouragement in a time of need is perhaps an indication of the failed Calvinist battle with spitefulness.) With union we receive justification and sanctification simultaneously, distinctly, without confusion or sequence. This means that we receive both the imputed righteousness and the infused righteousness of Christ. Which also means that we are both legally righteous and personally holy. Itâ€™s a win-win, again with the added benefit of leaving Lutherans in the dust of antinomianism since they allegedly donâ€™t configure union this way, donâ€™t receive sanctification at the same time, and so really are antinomian.
The added appeal of the union scheme has to do with the synecdoches of justification and sanctification, namely, faith and works (sorry cnh, whoever you are). If justification is used interchangeably with faith and sanctification with good works, which is a common usage both in the creeds and in the experience of believers, then union would appear to solve the antinomian problem, again by insuring that good works accompany justification and faith. In other words, via union, voila, I can look a Roman Catholic in the eye and tell him, when he accuses me of lacking virtue, â€œpound sand.â€ I mean to say, warm and fuzzy Calvinist that I am, â€œListen fellow, Iâ€™m united to Christ. Iâ€™m both righteous in Godâ€™s sight and I have good works steaming off my body. Go find a Lutheran.â€
Where this scheme breaks down, of course, is that justification and sanctification are both by faith alone. We are not justified by faith and sanctified by good works. In point of fact, justification and sanctification are acts, works of God. He is the one who declares a believer righteous. He is the one who quickens so that the believer lives to Christ.
Instead of solving the antinomian problem, then, union only makes the matter worse. By saying that I am both justified and sanctified simultaneously through union with Christ, the incentives for living a holy life virtually disappear. With the justification priority scheme, good works were a fruit and evidence of saving faith, in which case the believer would examine himself to see if he showed signs of grace. But with union, itâ€™s all good â€“ I am both righteous in Godâ€™s sight and I am infused with Christâ€™s righteousness, so conceivably I donâ€™t need to lift a good works finger.
Now to unionâ€™s credit, it does help us see more clearly that justification and sanctification are both equally by faith. It also clarifies that sanctification is as gracious as justification because it is all of God through the application of Christâ€™s redemption by the Holy Spirit.
But I donâ€™t see how it solves the antinomian problem. Justification, sanctification, and union are all about Godâ€™s good works. They are not about mine. So how am I, united to Christ, still not standing there next to my Lutheran friend, just as vulnerable to the Roman Catholic kvetch about antinomianism?