The Reformation doctrine of justification was not something about which Protestant theologians could afford to be tentative. At stake is not only the question of how a sinner stands accepted before God and, in connection with that, how he is assured of salvation (1 John 5:13), but also the goodness of God toward His people.
In the end, our controversy with Rome is important because Christ is important. Christ alone—not He and Mary (LG 62)—intercedes between us and the Father; Christ alone—not the pope (LG 22)—is the head of the church and, thus, the supreme judge of our consciences; Christ alone—not pagan “dictates of conscience” (LG 16)—must be the object of faith for salvation; and Christ’s righteousness alone—not ours (LG 40)—is the only hope we have for standing before a God who is both just and the Justifier of the wicked. To move to Rome is not only to give up justification and, thus, assurance— even more so, it is to give up Christ.