Petra's lineup fluctuated over the next several years; in spite of the instability, they managed to record their first breakthrough effort, Washes Whiter Than, in 1979, which featured the Christian radio hit Why Should the Father Bother. When the dust finally settled, the group consisted of Hartman, Volz, keyboardist John Slick, bassist Mark Kelly, and drummer Louie Weaver. The albums Never Say Die (1981), More Power to Ya (1982), and Not of This World (1983) did much to popularize the group, and in 1984, they were rewarded with a Grammy nomination for Best Contemporary Gospel Group and two Dove Award nominations (the first of many). For 1985's Beat the System, ex-Joe English Band keyboardist John Lawry replaced Slick. In 1986, Greg Volz left Petra for a solo career, and former Head East singer John Schlitt assumed vocal duties for Back to the Street. 1987's This Means War marked a successful transition to a less polished brand of rock & roll. Subsequent efforts, like 1988's On Fire!, which debuted bassist Ronny Cates, brandished a heavier guitar onslaught in the wake of Stryper's success as a Christian metal band, although Petra never neglected their trademark lush ballads. Petra has soldiered on through the '90s and into the 2000s with few signs of slowing down. 1995 saw Lawry replaced by Jim Cooper, and the addition of guitarist David J. Lichens. Subsequent efforts include 1998's God Fixation and 2000's Double Take. ~ Steve Huey, Rovi