How to Live the Victorious Life
Justification and sanctification are dual benefits which Christ won for man by His life, death and resurrection. Yet we cannot secure an interest in these benefits, we cannot share in them, unless we become one with Christ through faith-union. As Luther says, "He who believes shall possess all things, and he who believes not shall possess nothing."
Upon being united to Christ, we are justified, for "if the root be holy, so are the branches." Rom. 11:16. And if we are "in Christ," joined to Christ as the branch is united to the vine, it is inevitable that we will be "partakers of His holiness." Union with Christ therefore secures the two benefits. The legal benefit is justification, and the moral benefit is sanctification. It is impossible to secure one without the other. As Calvin says:
Why, then, are we justified by faith? Because by faith we grasp Christ's righteousness, by which alone we are reconciled to God. Yet you could not grasp this without at the same time grasping sanctification also. For he is "given unto us for righteousness, wisdom, sanctification and redemption." [I Cor. 1:30]. Therefore Christ justifies no one whom he does not at the same time sanctify. These benefits are joined together by an everlasting and indissoluble bond, so that those whom he illuminates by his wisdom, he redeems; those whom he redeems, he justifies; those whom he justifies, he sanctifies.—Ibid., chap. 16, sec. 1.