February 26 would have been Johnny Cash’s 81st birthday. Unlike many celebrities whose name dies out with the obituaries of their fan base, Cash continues to matter. And I think it matters that we understand why.

Cash remained—to the day of his death—a subject of almost morbid curiosity for a youth culture that knows nothing of “I Walk the Line.” At the 2003 awards show, 22-year-old pop sensation Justin Timberlake, beating Cash for the video award, demanded a recount. Why would twenty-something hedonists revere an old Baptist country singer from Arkansas?

In one sense, the Cash mystique was nothing new. For the whole length of his career, onlookers wondered what made him different from the rest of the Hollywood/Nashville celebrity axis. Much of it had to do with the “man in black” caricature he cultivated. Cash joked that fans would often say to him, “My father was in prison with you.” Of course, Cash never served any serious jail time at all, but he could never shake the image of a hardened criminal on the mend. People really seemed to think that he had “shot a man in Reno, just to watch him die.”

That’s probably because of just how authentic and evocative his songs of prison life were. “Folsom Prison Blues,” for instance, just seems to have been penned by someone lying on a jailhouse cot listening to a train whistle in the night: “There’s probably rich folks eating in a fancy dining car/ They’re probably drinking coffee and smoking big cigars/ Well, I know I had it coming/ I know I can’t be free/ But those people keep a’movin’, and that’s what tortures me.”

The prison imagery seemed real to Cash because, for him, it was real. He knew what it was like to be enslaved, enslaved to celebrity, to power, to drugs, to liquor, and to the breaking of his marriage vows. He was subject to, and submissive to, all the temptations the recording industry can parade before a man. He was a prisoner indeed, but to a penitentiary of his own soul. There was no corpse in Reno, but there was the very real guilt of a lifetime of the self-destructive idolatry of the ego.

It was through the quiet friendships of men such as Billy Graham that Cash found an alternative to the vanity of shifting celebrity. He found freedom from guilt and the authenticity of the truth in a crucified and resurrected Christ. And he immediately identified with another self-obsessed celebrity of another era: Saul of Tarsus. He even authored a surprisingly good biography of the apostle, with the insight of one who knows what it is like to see the grace of Jesus through one’s own guilt as a “chief of sinners.”

Even as a Christian, Cash was different. He sang at Billy Graham crusades and wrote for Evangelical audiences, but he never quite fit the prevailing saccharine mood of pop Evangelicalism. Nor did he fit the trivialization of cultural Christianity so persistent in the country music industry, as Grand Old Opry stars effortlessly moved back and forth between songs about the glories of honky-tonk women and songs about the mercies of the Old Rugged Cross.

To be sure, Cash’s Christian testimony is a mixed bag. In his later years, he took out an ad in an industry magazine, with a photograph of himself extending a middle finger to music executives. And yet there is something in the Cash appeal to the youth generation that Christians would do well to emulate.

Other Christian celebrities tried—and failed—to reach youth culture by feigning teenage street language or aping pop culture trends. How successful, after all, was Pat Boone’s embarrassing attempt at heavy metal—complete with a leather outfit and a spiked dog collar?

Cash always seemed to connect. When other Christian celebrities tried to down-play sin and condemnation in favor of upbeat messages about how much better life is with Jesus, Cash sang about the tyranny of guilt and the certainty of coming judgment. An angst-ridden youth culture may not have fully comprehended guilt, but they understood pain. And, somehow, they sensed Cash was for real.

The face of Johnny Cash reminded this generation that he has tasted everything the youth cultures of multiple decades have to offer—and found there a way that leads to death. In a culture that idolizes the hormonal surges of youth, Cash reminds the young of what pop culture doesn’t want them to know: “It is appointed to man once to die, and after this the judgment.” His creviced face and blurring eyes remind them that there is not enough Botox in all of Hollywood to revive a corpse.

Cash wasn’t trying to be an evangelist—and his fellow Bible-belt Evangelicals knew it. But he was able to reach youth culture in a way the rest of us often can’t, precisely because he refused to sugarcoat or “market” the gospel in the “language” of today’s teenagers.

One of Cash’s final songs was also one of his best, an eerie tune based on the Book of Revelation. His haunting voice, filled with the tremors of approaching hoof-beats, sang the challenge: “The hairs on your arms will all stand up/ At the terror of each sip and each sup./ Will you partake of that last offered cup?/ Or disappear into the potter’s ground/ When the Man comes around?”

Cash’s young fans (and his old ones too) may not have known what he was talking about, but they sensed that he did. They recognized in Cash a sinner like them, but a sinner who mourned the tragedy of his past and found peace in One who bore terrors that make Folsom Prison pale in comparison.

A version of this article originally ran on February 25, 2012.