Q & R: What Makes Someone a Christian?

Here’s the Q:

I recently started reading your new book, and it’s already made me think about quite a few things. But, over the past few weeks, I’ve been asking as many people as I can the following question: What makes someone a Christian?
I am assuming your book will help me get a take on your answer(s) to this question. But, if not, I’d love to hear what you think about it. I’m an ex-evangelical pastor, but more recently I’ve come to – at the least – accept Christianity as primarily a socio-cultural identity (as Richard Dawkins defines himself, a “cultural Christian”). Beyond that, is “Christian” primarily a noun, an adjective, or a verb? Should we, like Kierkegaard, say we shouldn’t actually call ourselves a Christian? Or, like Bono, say that we’re trying to be a Christian? Many people simply equate orthodox Christianity with Christianity itself, but this seems to defy the historical usage of the word (i.e. Mormons, Jehovah’s Witnesses, many other “unorthodox” Christian groups, or even someone like Pete Rollins). Or, many people will say that to be a Christian necessarily means that a person is actively involved in some concrete version of Christian community. Is there an objective list of beliefs or actions that one must agree with or perform in order to “deserve” the label? Or, as Roger Olson has suggested, that Christianity is a “centered set” that defines itself by Jesus, but does not have any “boundaries” as to who’s in or out?
This seems like a very difficult, multi-layered question to answer. I will keep reading your book, but if you don’t specifically address this question, I’d be interested to hear your response.

Here’s the R:
Thanks for your question. I’m sure many will be struck, as I am, that an “ex-evangelical pastor” would see this as an important question to ask. I think you’re right. It is. I remember being with an Eastern Orthodox priest once who, very graciously, let the rest of us Protestants and Catholics know that we weren’t part of the True Church and that we didn’t participate in true worship. (He said we were engaged in “popular piety” and nothing more.) I frequently hear from readers (actually, most of them aren’t actual readers, but have read something about me on someone else’s website, etc.) who tell me that I’m not a Christian because I don’t uphold their preferred atonement theory or doctrine of biblical inspiration vigorously enough. So there’s no end to this kind of “who’s-in, who’s-out” activity.
I think your question is important and it opens up important conversation, but I think it’s impossible to answer without saying, “To me…” or “to us…” I think you’ll find an interesting twist on this question when you come to Chapter 20 (where you’ll see my friend Pete Rollins quoted, by the way).
Your question opens up the whole subject of religious identity which I grapple with in the book – as you say, not simply as a theological or institutional question, but as a social, psychological, and even political one. I think you’ll find a lot to further stimulate your thinking as you continue reading. In the meantime, here are a few relevant words from Jesus himself:

Why do you all me “Lord, Lord,” and do not do the things that I say?
Many of the first will be last, and the last, first.
As much as you did it to the least of these my brothers, you did it to me.
A tree is known by its fruit.
If you love your friends only, what good is that? Don’t even the tax collectors do that?
By this will all people know you are my disciples, if you love one another …

He has a way of mixing things up, doesn’t he?!