Most of the time, Christian Rock essentially follows the sonic blueprint of mainstream AOR and arena rock, except of course for its Christian-themed lyrics. It was initially a somewhat controversial style in Christian circles, as more conservative elements believed all rock & roll to be inherently evil by nature, and gospel radio programmers were accordingly reluctant to program the music when it appeared during the mid-'70s. But others began to see Christian rock as an effective way to reach the unconverted, wrapping spiritual messages in an attractive package that strongly resembled a highly popular mainstream musical style. Petra's two Dove Award nominations in 1984 effectively signaled the gospel music community's acceptance of Christian rock as a viable and legitimate form, and helped pave the way for the heavier, flashier Christian style known as heaven's metal (itself an attempt to hook secular fans with an already established sound and spiritual lyrics). Harder, more uptempo Christian rock songs often try to project a firm, tough-minded, unshakable religious attitude, in keeping with the aggressive sound of the music, although many Christian rock bands have a fondness for majestic, sweeping power ballads; in both cases, the polished, squeaky-clean production is often just as close to the sheen of CCM pop as to the already slick sound of much AOR. Although some Christian rock bands experimented with rawer, more biting sounds in the late '80s and early '90s, the associations between the established conventions of big, anthemic hooks, loud yet smoothed-out guitars, and intense (yet fundamentally safe) spiritual emotion never completely died down. That time period also witnessed the unique phenomenon of King's X, a band with roots in Christian rock which garnered a devoted cult following among secular listeners and critics, thanks to its willingness to deviate from established musical formulas and address spirituality in more general terms. As alternative CCM began to capture larger portions of the Christian rock audience during the mid- to late '90s, many Christian rock heavyweights conceded the impact of mainstream alternative rock and shifted their brands of hard rock accordingly, although Petra soldiered on into the new millennium with their sound virtually unchanged.