When did Christianity become the world’s largest religion?

A question came across my desk the other day: When did Christianity become the world’s largest religion?

For me, I don’t know if the when matters as much as the how? What does it mean to instead dig into the unconventional way Christianity came to surpass all other major world religions?

First, some context: Christianity is an approximately two-thousand-year-old religion, based entirely on the life and teachings of Jesus. Christianity is made up of the Roman Catholic church, Eastern Orthodox churches, and Protestant churches – all which is encompassed by over 43,000 different denominations to choose from.

Under the Protestant umbrella alone, your Southern Baptist lives alongside your Episcopalian; your evangelical shares a cup of tea with your Quaker brethren. The faces of Christianity, in other words, are many, even if we hold Jesus and the bible in common.

Here, this is also where division also starts, for this is where we start to draw lines in the sand. This is where it easily becomes more about who’s in and who’s out rather than how all are in, regardless of denominational interpretation: Yeah, but I’m not “that” type of Christian, someone will say, “that” meaning liberal, “that” meaning conservative, “that” meaning of which I am most definitely not.

So, how does a religion that is still considered a baby by some standards (at least when you compare it to a philosophy of religion like Daoism that birthed in the 6^th century BCE), become the world’s largest religion?

The answer is simple: through missionaries and colonizers.

Another writer puts it like this: “Beginning with the son of a Jewish carpenter, the religion was spread around the world first by Jesus’ disciples, then by emperors, kings, and missionaries. Through crusades, conquests, and simple word of mouth, Christianity has had a profound influence on the last 2,000 years of world history.” A profound influence, indeed, given that Christianity now boasts over two billion followers (and, according to another report, close to three billion adherents).

Anyone who’s taken church history can tell you that the church’s history is not the prettiest – because when religion mixes with power, and when this power is abused in the name of Jesus, someone will inevitably end up on top, to the detriment of others.

We saw this in the history of the Crusades. We saw this in the American institution of slavery (as well as other forms of slavery across the world). And we saw this during the Holocaust, when Christian teachings shaped anti-Sematic beliefs.

Given its rather sordid history, it makes me wonder how Christianity is still growing in leaps and bounds – and I say this as someone who has given her life to the Church, who somehow can’t not believe in what oftentimes feels like the wildest story of all: a virgin birth. A human who was God. The son of a lowly carpenter who died on a cross and rose again three days later.

But it also helps me understand why people are leaving Christianity for good.

In the last week alone, I’ve had three distinct conversations about the recent Pew Research study estimating that Christianity will not be the leading religion in America by 2050. According to an NPR report, although the Christian majority in the U.S. has been shrinking for decades, “as of 2020, about 64% of Americans identify as Christian. Fifty years ago, that number was 90%.”

It’s not that previously-identifying Christians are leaving Christianity for another religion. Instead, most are becoming unaffiliated with any sort of religion altogether, now identifying as atheists, agnostic or nothing in particular. Perhaps they find a home in the Deconstruction or Exvangelical movements; perhaps they still cling to a higher power, even if that higher power is no longer called God.

To me, none of this is anything new.

I have lived all of my life on the West Coast, and most of my adult life in the greater San Francisco Bay area. When I was on ministry staff, I served in an area that was 96 percent unchurched (and this was over a decade ago; I imagine those numbers have only increased). I do not know what it is like to live in a place that is predominately made up of Christians, where there is a church on every corner and you greet people by asking them what church they attend.

This I do not know, even if I can tell you stories about it. But what I can tell you is that we do not need to be afraid.

Jesus wasn’t fixated on numbers: that’s something his followers have created on his behalf.

Theologians often write that a “Great Rummage Sale” happens every 500 years or so in Christianity. (Phyllis Tickle’s The Great Emergence has my favorite explanation on the topic). We’re due for another sale. We’re in the midst of another sale.

And I think we’re going to be just fine on the other side.