I have said often that justification by God's grace through faith in Jesus is the core of our belief. I have never been ambiguous about that.
It would be easy to debunk Brian's rigid, narrow, exclusive, and church-dividing dogma

(sorry, breaking my rule about smileys lest anyone not get the irony) by pointing out how many, many honest followers of Jesus have believed in salvation by works, and done so with the same genuine sincerity that Brian believes in salvation by grace (and they can't be "wrong" of course, but merely in disagreement), and to point to James and many other places that specifically call Brian's view into question, throw in some speculation about non-canonical Scriptures attesting to the long tradition and practice of teaching salvation by works in the early church, go on to the Church Fathers, focus on the close of the Athanasian Creed, add a little Reformation history of "disagreements" (again, no one was wrong, because that would be to sacrifice unity) and easily call salvation by grace into question. And then, when refuted, merely keep raising the questions, keep acknowledging that I'm not against salvation by grace, I'm not saying it is wrong, I'm merely saying it is one of the possibilities, and the Church is big enough to celebrate diversity of soteriologies, you know, by comparing the works/grace debate to such adiaphora as meat/vegetables. The key, of course, would be an air of exasperated patience, a constant sense of "Sigh...let's try this again...grace is good, but so are works...we can't claim the status of "right" for ourselves and "wrong" for those who disagree on the matter of salvation by grace through faith because so many faithful Christians have proclaimed salvation by works..." and then start the whole process over. But even as a joke, applying the acid drip of constant questioning to established Christian doctrine is distasteful to me.
A more constructive response is to say that I agree totally with Brian on the words, but not on what the words mean. Salvation by grace through faith is indeed the central doctrine, but all the other doctrines define the terms. Eph. 2:8-10 or John 3:16 or what-have-you are at the heart of it, and all the rest of the Christian doctrines merely explain what those short statements mean. You could take a multi-volume dogmatics text and re-organize it along the words of John 3:16 (vol. 1 God (trinity), vol. 2 Love, vol. 3 World (creation), vol. 4 Gave (grace), vol. 5 Only-begotten Son (two-natures Christology), vol. 6 Whovever (election), vol. 7 Believes (nature of faith), vol. 8 In Him (ridiculousness of inclusive language

, vol. 9 Should Not Perish (original sin, damnation), vol. 10 But Have Everlasting Life (eschatology, heaven, new creation, etc.). And having written that dogmatic series, you'd discover you'd said all the same things that are currently in standard dogmatics texts, except you'd see how John 3:16 doesn't mean anything without the rest of Christian doctrine, just as the heart has no purpose or life apart from the rest of the body. Nobody can say "Jesus is Lord" apart from the Holy Spirit, and nobody who makes the Jesus the Lord in real life condones sodomy. Sexual morality is not unrelated to the central doctrines, as the NT repeatedly makes clear. Doctrine is an organic unity.