Question: What do Roman Catholics, Greek Orthodox, Russian Orthodox, Baptists, Methodists, Lutherans, Presbyterians, Episcopalians, Jehovah’s Witnesses, Seventh-Day Adventists, Amish, Mennonites, Quakers, Pentecostals, charismatics, evangelicals, fundamentalists and “non-denominationals” all have in common?

Answer: they’re all “Christians.”

Christianity is the largest religion in the world. Christians account for about 32% of the total global population, and about 80% of the total U.S. population. But those numbers, and that label “Christian,” covers a vast amount of diversity.

That diversity is lost whenever one particular group of Christians narrowly decides that the term “Christian” properly applies only to their own group alone (and perhaps also to some others, whom they may deem sufficiently similar to their own, to also deserve the right to use the “Christian” label).

It has been estimated that some 34,000 distinct Christian faith groups exist.  Such sheer diversity encompasses a broad range of contrasting views on matters ranging from theology and salvation to ethics and social issues. Christian branches, sects, and denominations run the gamut from liberal and progressive, through moderate, to conservative and fundamentalist.

Sometimes Christians at one end of this vast spectrum decide that their own version of Christianity is the only really valid one. They may look askance at fellow Christians at the other end of this broad spectrum, and perhaps even question whether those other understandings or interpretations of Christianity really even deserve the name “Christian.”

But of course, everything is relative, so those at that other end of the spectrum may likewise question the credentials of those whose views as to just what Christianity “really is” may likewise be far removed from their own.

I have often overheard Christians of one particular sort make clear distinctions, in their conversations, between “Catholics” on the one hand and “Christians” on the other, as if the two terms referred to two entirely different things. I have even had students in my world religions courses tell me, quite bluntly and matter-of-factly, that “Catholics aren’t Christians,” as if the term “Christian” referred strictly to their own evangelical Protestant form of Christianity alone.

Many who speak and think like this seem unaware of the fact that their own evangelical Protestant form of Christianity (or whatever form of Christianity they may practice) is, itself, actually only one particular form or version of Christianity — and far from the most predominant or most popular or most widespread form.

Within the U.S., evangelical Christians amount to only about 26% of the population.  Mainline Protestants (non-evangelical denominations such as Methodists, Lutherans, Presbyterians, etc.), together with historically black denominations (such as the African Methodist Episcopal [AME] Church, or the Church of God in Christ [COGIC]), together comprise 25% of the American population. And Catholics make up another 24% of the total U.S. population.

Taken together, American Catholics, mainline Protestants, and historically black denominations total some 49% of the American populace. American evangelicals are thus outnumbered by non-evangelical Christians by almost two to one.

On the wider global scene, the gap is even greater. Of the 32% of the total world population that identifies itself as Christian, fully half are Catholic. It is estimated that there are currently about two billion Christians in the world, so about one billion of them are Catholics. That’s a billion individuals who, I suspect, would be very shocked to be told that they are not “true” Christians.

Of course, pollsters do not split hairs over who is or is not a “true” or a “real” Christian. They take people at their word; if someone says they’re a “Christian” (of whatever sort), then objectively they’re a Christian — end of story. Subjectively, of course, lots of Christians question the very Christianity of many other Christians, whose alternate forms or versions of Christianity may not square with their own.

Are Catholics Christian? Catholics certainly think so. Many Protestants would agree. Other Protestants may have their doubts, depending of course upon how strictly or narrowly they may define “Christianity” for themselves.

Are Mormons Christian? The same kinds of issues and stances apply to this sort of question, too. Mormons, for their part, insist that yes, of course they are Christians. Pollsters take them at their word, as being self-identified Christians. Many other Christians also accept Mormons as being legitimately Christian in nature. Still other Christians (many of them theologically conservative evangelicals) may express reservations, and even grave doubts.

“Evangelical Christians should not vote for Mitt Romney because he’s a Mormon, therefore not a real Christian,” asserted Robert Jeffress, senior pastor of First Baptist Church of Dallas, late last year. Jeffress further explained that “the Southern Baptist Convention, which is the largest Protestant denomination in the world, officially labels Mormonism as a cult.” A few years earlier, a Florida evangelical preacher named Bill Keller sternly warned his readers: “If you vote for Mitt Romney, you are voting for Satan!” 

It would seem that these sorts of questions — who is, and who is not, a “Christian”? — are not always merely idle or abstract questions, of interest only to armchair theologians. They can evidently have significant wider social impact, potentially influencing even the outcome of U.S. presidential elections.