On a recent weekend trip to New York City, I bolted from Ground Zero over to Wall Street, wanting as little time in the numbing cold as possible, and took refuge in the warmly lit interior of Trinity Episcopal Church for a service of Evening Prayer. Immediately on arriving, I noticed a large advertisement for an upcoming lecture by Sara Miles. Her crinkly, makeup-less smile brightened the banner, eliciting an involuntary smile from me in return, and her name was written in a conspicuously large font. Trinity Wall Street, as it's popularly called, is one of the wealthiest churches in America (its assets are worth somewhere in the neighborhood of $2 billion). It is—not to put too fine a point on it—the last place on earth Sara Miles would have been seen a few years ago.

Working as a journalist in Nicaragua in her young adulthood, Miles had turned her back on her own country's red-state politics in the Reagan years and embraced an itinerant life. As she describes in her 2007 memoir Take This Bread, she did a stint among Central American revolutionaries and their underground networks, documenting their lives and relentlessly questioning the ease with which her fellow North Americans applied labels like "communism" or "imperialism" in order, as often as not, to be spared the messy business of grappling with genuine human complexity. When she wasn't living in barrios and sharing the fear and physical hunger of her journalistic subjects (their food "always tasted of dirt [or] cheap grease," she said), she worked as a cook in New York. Hers was a life in which she "never heard a Gospel reading, never said the Lord's Prayer," never had occasion to see or care about stained glass or crucifixes or fonts. And yet, here she was at Trinity Wall Street all those years later, being advertised as a figure of the Episcopal establishment. Or so one could be forgiven for assuming. What gives?

Miles' newest book, City of God: Faith in the Streets, is, in part, about her discomfort with the juxtaposition I've been describing. Now a priest herself, some years after her entirely unexpected conversion at St. Gregory of Nyssa Episcopal Church in San Francisco at age forty-six, Miles has grown no less uncomfortable with the trappings of ecclesial life than she was in her twenties. "You just don't like church all that much," the rector at her parish recently told her, and she couldn't exactly deny it, despite the fact that she had an office there. In City of God, she tries to dissect her discomfort, exploring why she can't simply consider herself "a solitary 'priest of Jesus,' unencumbered by and superior to the Church that baptized me and gave me communion," but also why she can't easily embrace parish life as-is, without attempting to alter its encumbrances, stretching them into a more outward-oriented, mission-focused shape.

The book describes what is by now a familiar practice among many Anglicans: taking Ash Wednesday services on the road. Miles and some of her fellow clergy, robed in their full clerical vestments, set up tables around the Mission, her neighborhood in San Francisco, and imposed ashes on whomever they could entice into stopping by for a few moments of reflective prayer. Sometimes they would hand out flyers for their church services, and sometimes they would include pointedly political prayers that demonstrated they weren't concerned with an archaic Christian ritual that had nothing to do with social justice. But always there was the thumb dipped in ashes and pressed onto the forehead of the passersby. "Remember that you are dust," Miles would say, tracing the sign of the cross on people's skin, "and to dust you shall return."

The bulk of her book is a collection of stories or brief anecdotes—almost all of them written with artful, exquisite simplicity and unaffected candor, and some of them a good deal more powerful even than that—about the ways she has glimpsed grace and hope in these "Ashes to Go" services. Included, also, is an overarching theological interpretation: By taking ashes to people in the streets, Miles learns that the gospel "isn't rooted in morals: do this, then God will approve … . The good news of Ash Wednesday, the blessing so many people seek so fervently, comes from acknowledging the truth: that we are all going to die"—and that God reaches out to us in that very mortality, not because of our efforts at self-improvement but in spite of them. We must embrace the chaos of the streets, Miles decides, if we hope to have a chance of understanding what God is doing in the serenity of the liturgy.

To her credit, Miles incorporates dissenting voices in her narrative. She quotes one critic as saying, "Taking the imposition of ashes out of a liturgical context that includes scripture readings, the invitation to a holy Lent, and the litany of penitence, there is no insistence on the reality of sin or any call to repentance." In the interest of full disclosure, as an Anglican of a very traditional sort myself, I should confess that I share this worry. I fret over whether "Ashes to Go" reduces Christian symbolism to its lowest common denominator, watering down the call of the gospel to name Jesus as rescuer but also judge. Still, I have to admit that ashes have never been considered a sacrament in the Christian tradition, and imposing them on pedestrians is not the same thing as if one were taking the Eucharist to the market square and offering it on the spot to anyone who wanted it. And perhaps ashes—simple and almost caustically stark; a reminder of mortality—are the ideal gateway drug to lure people into a full-fledged Christian faith. Perhaps "Ashes to Go" will be the thing that causes some people to receive, say, "Baptism to Stay." As an Episcopal bishop friend of mine once put it, after his first experiment with the practice, "I see Ashes to Go as a sort of 'pre-evangelism.' "

For Miles, taking part in this unconventional form of pre-evangelism has, she says, re-evangelized her. After several years of street-side Ash Wednesday liturgies, she is better able to picture the heavenly city the way she believes it will actually look—"like the 'New Jerusalem' bodega run by Syrian Christians that I trudge past on my way to work, its dingy pink front plastered over with Miller beer signs, its enthusiastic, unshaven owner waving and smiling each new day as he opens the door to welcome in a straggling, polyglot parade of schoolkids, nurses, winos, and day laborers." Reading that, I can't help but recall the ending of "Revelation" by Flannery O'Connor, in which Mrs. Turpin receives a vision of "a vast horde of souls … rumbling toward heaven": "whole companies of white-trash, clean for the first time in their lives, and bands of black niggers in white robes, and battalions of freaks and lunatics shouting and clapping and leaping like frogs"—the population of the city of God. That vision of a motley contingent of pilgrims, foreheads all bedaubed with ashes, making their way to their celestial habitation is the gospel Miles has heard afresh. That's the substance of her renewed eschatological hope.

This past Ash Wednesday, for the first time, I participated in an Ashes to Go service of sorts, although not on the street but in a hospital. After ducking out early from the morning Eucharist at the seminary where I teach, I scrubbed the ashes from my forehead, got in my car, and drove to the Hillman Cancer Center in Pittsburgh, where I met my priest friend Sean. Together with another friend, we took the elevator to the seventh floor and found our beloved colleague and friend Martha's room. Diagnosed a couple of months earlier with acute myeloid leukemia, she was beginning to show signs of her three rounds of chemotherapy. Her arms were reddened with rashes, and her bald head was shawled with a hand-knit scarf. She was visibly weakened, but I smiled at the photo on her wall, taken several weeks earlier on a visit to an antique store during which she had donned a facsimile of a Roman soldier's helmet and brandished a broadsword, teeth clenched in mock rage. There was still plenty of fight left in her, I said, and she agreed.

After some chitchat, we opened our prayer books and read the penitential liturgy. Then Sean read the epistle: "We are treated as … dying, and behold, we live." As Sean pressed his sooty dark thumb onto Martha's taut, too-shiny skin, I bit my lower lip. Never had the apostle's words seemed so immediately, obviously convincing to me. Rarely had the gospel seemed so stunningly addressed to real human need. "To dust you shall return," Sean intoned in his deep, uninflected voice. Yes, I thought, but not for good.

As we left the hospital room, I pulled out my phone and tweeted: "If I'm getting ashes to go, a hospital is the place I want to get them."

I think that's what Sara Miles is trying to say, too.

Wesley Hill is assistant professor of biblical studies at Trinity School for Ministry in Ambridge, Pennsylvania. His next book, Paul and the Trinity, is forthcoming from Eerdmans.

Copyright © 2014 by the author or Christianity Today/Books & Culture magazine.
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