John Allen Jr., one of the keenest observers of the Vatican, has called Francis a “pope for the Catholic middle,” positioned somewhere between the church’s rigorists and the progressives who pine to Episcopalianize the faith.

But the significance of this positioning goes beyond Catholicism. In words and gestures, Francis seems to be determined to recreate, or regain, the kind of center that has failed to hold in every major Western faith.

So far, he has at least gained the world’s attention. The question is whether that attention will translate into real interest in the pope’s underlying religious message or whether the culture will simply claim him for its own — finally, a pope who doesn’t harsh our buzz! — without being inspired to actually consider Christianity anew.

In the uncertain reaction to Francis from many conservative Catholics, you can see the fear that the second possibility is more likely. Their anxiety is not that the new pope is about to radically change church teaching, since part of being a conservative Catholic is believing that such a change can’t happen. Rather, they fear that the center he’s trying to seize will crumble beneath him, because the chasm between the culture and orthodox faith is simply too immense.

And they worry as well that we have seen something like his strategy attempted before, when the church’s 1970s-era emphasis on social justice, liturgical improvisation and casual-cool style had disappointing results: not a rich engagement with modern culture but a surrender to that culture’s “Me Decade” manifestations — producing tacky liturgy, ugly churches, Jonathan Livingston Seagull theology and ultimately empty pews.

Francis seems acquainted with that danger — witness his warnings against a church that just “becomes an N.G.O.,” or against reducing Christianity to “taking a spiritual bath in the cosmos.”

But the test of his approach will ultimately be a practical one. Will the church grow or stagnate under his leadership? Will his style just win casual admirers, or will it gain converts, inspire vocations, create saints? Will it actually change the world, or just give the worldly another excuse to close their ears to the church’s moral message?

By his fruits we will know — but not for some time yet.