Mark Shea has forgotten the basics of Evangelical faith, suggesting that the only options are 1) authoritative pope or 2) relativism. If you don’t have a magisterium, he argues, all you have is private judgment, and thus any discussion between, say, a Mormon and an Evangelical must be a toss-up (and for that, he says, Luther is to blame!).
First, what did Luther say? He pointed to the fact that “it is as clear as the day that popes and councils have frequently erred and contradicted each other,” and thus the individual conscience must be bound by the Word of God, and that this, and the overarching principle of the Gospel, must be the criteria judging popes, councils, and the individual pronouncements of all teachers, whether Christian or Schwaermer. That’s not relativism–it’s the evangelical response to the arbitrary swings through history of magisterial positivism.
Card, the Mormon, muddles two different issues–what should other Christians think theologically of Mormonism, and what role religion should play in secular political debates. He thinks that the definition of Christian should be based on American democratic values–everyone gets a vote. He acknowledges Mormon beliefs are different from everyone else, that they don’t accept anyone else’s baptism or authority or teachings. He wants the criterion of political discussion, religious tolerance, to be the criterion of theological discussion as well.
Mohler, on the other hand, says there’s nothing subjective about the matter. There are objective criteria to guide us, including Scripture and the ecumenical creeds. Luther, Calvin, Zwingli, Bucer, Knox, Oecolampadius, Melanchthon, Cranmer–all the Reformers held to the same criteria, by which they judged both Rome and those Luther dubbed the Schwaermer.
Pace Card, these are criteria that Catholicism also accepts as distinguishing between Christian and non-Christian; thus, while the Catholic Church regards Luther, et al., and their heirs as heretical, it still accepts them as Christian. The Catholic Church is able to make this distinction because of its acceptance of the “hierarchy of truths”–there are some non-negotiables which constitute the sine qua non of Christian faith–in particular, the Trinity and Christology. Other Christians may be off on many things, but if they have a valid baptism (water and the Triune name), and orthodox Theology and Christology, they are Christian. That’s the starting point for ecumenism.
Mormonism is an anomaly. Neither Catholicism nor Orthodoxy nor Protestantism accepts it as Christian. And we all use the same criteria–its theology is not Scriptural, nor is it in accord with the earliest summaries of Christian faith.
Shea, however, doesn’t seem to have the concept of the hierarchy of truths in his theological vocabulary, so is unable to make any meaningful distinction between a Lutheran and a Mormon, as we see in the article to which he links.