From Richard Gaffin, "The Vitality of Reformed Systematic Theology," in The Faith Once Delivered (P&R, 2007), 16-7:
For justification, it is fair to say that, in general, Reformation theology has grasped, at least intuitively, the escathological "now" empathically asserted, for instance, in Romans 5:1 and 8:1. It has perceived with sound instinct that the verdict pronounced on believers, declaring them righteous and entitled to eternal life, involves, judgment, already realized, that is final and irrevocable. But it has been much more inhibited, no doubt because of polemics with Rome, in recognizing and incorporating into its doctrinal formulations the still-future aspect of justification clearly implied if not explicitly taught in the New Testament. The Westminster catechisms, for instance, confess that believers will be 'openly acknowledged and acquitted in the day of judgment.' Such language is thoroughly forensic, and acquittal is at the heart of justification.
The integral tie between that future acquittal and present justification needs to be made clear. As a single justification by the sole instrumentality of faith and based exclusively on the imputed righteousness of Christ, the one is the consummation of the other, as its open manifestation. For now until Jesus comes, the believer's justification is most certainly settled and certain but not uncontested. Romans 8:33-34, for instance, is clear in that regard. The faith that justifies perseveres in love (Gal. 5:6). No doubt, as so often in our theologizing, the proverbial razor's edge between the truth of the gospel and serious error presents itself here, a narrow ledge that will have to be negotiated with care.