Check out Touchstone Magazine for this brilliant piece on Johnny Cash. The whole article is tremendous, but the last few paragraphs are so accurate and profound that I have to reprint them here in their entirety. (By the way, you can listen to my recent sermon on Johnny Cash here. I touch on some of these same themes, although far less eloquently.)

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 MTV culture has 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 MTV 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.

Johnny Cash is dead, and there will never be another. But all around us there
  are empires of dirt, and billions of self-styled emperors marching toward judgment.

Perhaps if Christian churches modeled themselves more after Johnny Cash,
  and less after perky Christian celebrities such as Kathy Lee Gifford, we might
  find ourselves resonating more with the MTV generation. Maybe if we stopped
  trying to be “cool,” and stopped hiring youth ministers who are
  little more than goateed game-show hosts, we might find a way to connect with
  a generation that understands pain and death more than we think.

Perhaps if we paid more attention to the dark side of life, a dark side addressed
  in divine revelation, we might find ourselves appealing to men and women in
  black. We might connect with men and women who know what it’s like to
  feel like fugitives from justice, even if they’ve never been to jail.
  We might offer them an authentic warning about what will happen when the Man
  comes around.

And, as we do this, we just might hear somewhere up in the cloud of witnesses
  a voice that once cried in the wilderness: “Hello, I’m Johnny Cash.”

Don Johnson Evangelistic Ministries