Toeing the Hollywood line on Johnny.(Now Playing: film reviews diamonds to dross)(Johnny Cash)

Like public squares at Christmas time, movies today are under pressure to be purged of any hint of religious faith.

How else to explain Walk the Line, a musically rousing but factually ignorant movie biography of Johnny Cash?

This proudly religious singer-songwriter's story was one of moral failure and eventual redemption, with Christian faith as his saving grace. Yet Hollywood here reduces the man's life to the usual sex, drugs, and rock 'n' roll cliches. If it weren't for the presence of Cash's music--among the most distinctive of American sounds-you could drop just about any rock star of the twentieth century into this film without altering the storytelling much.

Knowledgeable Cash fans will find the biographical omissions annoying. Everyone, though, will enjoy the music to which the movie is dedicated. Using Cash's chugging rhythms and plowing bass as a metronome, Walk the Line struts with a seductive swagger during its many musical numbers. It opens with a wallop, as "Folsom Prison Blues" rumbles through the walls of San Quentin State Prison, where Cash performed live in 1969.

Joaquin Phoenix, best known as the conniving Commodus of Gladiator, does Cash justice with his hound-dog vocals and heavy lids. Phoenix sings on the soundtrack, and while he doesn't deliver as spot-on a piece of mimicry as Jamie Foxx did in the recent Ray Charles biopic, he's adept at capturing his subject's conflicted spirit. Too bad the filmmakers didn't allow him to carry his portrayal all the way through to the dramatic transformation that his subject eventually underwent.

Instead, director James Mangold and co-screenwriter Gill Dennis traverse the well-beaten path of the rock-star bio, following a storyline eerily similar to last year's Ray. There is the perfunctory treatment of childhood tragedy--in both Cash and Charles's cases, the death of a brother--along with a few nods to the church songs that inspired the boy's musical talent. The movie presents such religious influences as quaint at best--sort of a cute, country-bumpkin aspect of growing up.

From there the movie jumps into Cash's early success, where the more sensational aspects of his life can be mined to full effect. Cash's first wife, ...