The second half of the 90s was the first explosion of christian music in the mainstream, not just with the successes of christian bands like DC Talk, Jars of Clay, Sixpence None the Richer, Third Day, Delirious? and The Newsboys, but also with the spiritual (some of it specifically christian) hard-rock of mainstream bands like Creed, Live, Collective Soul & Lifehouse, which helped legitimize christianity for the younger generation.
At the start of the '00s, heavy rock band P.O.D (Payable On Death) who had been largely releasing albums for the christian market for the past 7 years, had a major success with the album Satellite, which reached #6 in the USA. The songs "Youth of the Nation" and "Alive" were radio hits.
The decade became similarly accomodating for heavy rocking christian bands like Switchfoot, Underoath, Skillet, Flyleaf, Anberlin, Red, Mutemath & Demon Hunter. As with Creed in the late 90s, there were also many bands in the mainstream who admitted their christian beliefs while not keeping a tight relationship with the christian market, like Evanescence, Paramore, As I Lay Dying, Shinedown, MxPx, meWithoutYou, The Classic Crime, Blindside & The Fray. The music sections at christian bookstores would've started to look more & more like the shelves of mainstream music stores.
It's important to note that the VAST majority of contemporary christian musicians have been American. Two prime examples of successful CCM bands outside of the US are Delirious from the UK and The Newsboys, originally from Australia.
It's my assumption that in the past decade, with all the developments in popular christian music, there would've been more "Private Christians" than all previous decades, that is, people who pursue christianity outside of church and especially draw inspiration privately from christian or pseudo-christian rock music. In the coming decade though, there may be less need to be private as churches may be more accomodating to the past generation.
Michael W Smith had his breakthrough in 1990, after having released albums for most of the 80s. The album Go West Young Man wasn't a huge success, but the inspirational song "Place in This World" did exceptionally well in reaching #6 on the US pop chart and probably no other christian song has charted quite so well since. After the similarly successful album Change Your World, Smith had a massive US success with the worshipful album I'll Lead You Home and has recorded similar albums since.
King's X, the arty, heavy rocking band, who were classed as a christian band against their wishes, had their first success with their Faith, Hope and Love album in 1990. It made #85 on the US Albums chart and #70 on UK Albums. It also made #31 on the US Contemporary Christian Albums chart. Despite their claiming to not be a christian band, it could be said that King's X was christianity's most respected band for the first half of the 90s. Another thing is, where a lot of christian bands can be accused of merely copying popular mainstream music, King's X, with their creative, psychedelic, heavy metal, could never be accused of that. More likely that other bands have copied them!
Before retracing to the 80s, I'll note the mainstream rock band Giant, led by guitarist/singer Dan Huff, a man who had been guitarist in the christian rock band White Heart and continued to assist other christian musicians, including Michael W Smith, in their albums. Giant managed small successes with their album Last of the Runaways and songs "I'm a Believer" and "See You in My Dreams".
Stryper, performing 80s-pop-metal, assured the youth of the 1980s that Christians can have outrageous hair, make-up and tight leather outfits and rock out too!!. Possibly it was the novelty of having a christian pop-metal band that made them so popular in the mainstream. They had top 40 albums, To Hell With the Devil, In God We Trust and Against the Law in the second half of the 80s. Their 1986 ballad "Honestly" made the US top ten.
Amy Grant was arguably the first ever christian musician to have a hit album with the masses. Unguarded, in 1985, reached #35 in the US and the song "Find a Way" reached #29 in US singles. Her next album Lead Me On only reached #71, though many of the songs from the album performed well on the US Adult Contemporary Pop chart. Her 1991 album Heart in Motion, was the peak of her mainstream success. The album had something of a sexy, mainstream feel to it and would have been quite new territory for christian music, but it still had something of a familiar CCM sound to it. The album reached #10 in US Albums and charted in countries all around the world and the two songs "Baby, Baby" and "Every Heartbeat" were massive hits. From here on, Grant backed off from the mainstream a little had most of her success on the christian and adult contemporary charts.
A man who was an important part of CCM's success was Wayne Kirkpatrick, a songwriter who wrote for a range of artists both christian and mainstream. He was particularly associated with Michael W Smith and wrote for him on a number of his successful albums and he also contributed to Amy Grant's Heart in Motion album. One of Kirkpatrick's most successful mainstream contributions was "Change the World" (co-written with two other writers) which was a big hit for Eric Clapton in 1998.
Another important behind-the-scenes man was John Elefante who produced many christian rock albums from the mid-80s onward, most notably Petra. Elefante had actually begun his career in the spotlight, being hired to replace Steve Walsh as the singer in the successful American rock band Kansas. Elefante sung and played keyboard on the 1982 Kansas album Vinyl Confessions and also contributed to much of the songwriting on the album.The album was strongly influenced by his own christian beliefs as well as those of veteran Kansas member, Kerry Livgren.
In 1981, Daniel Amos, the one time christian country-rock band led by singer-songwriter Terry Scott Taylor, released the album Alarma! an arty, concept album surely unlike anything ever before released by a christian band. This started a movement within CCM of arty music, including bands like The 77s, The Choir, Lifesavers Underground & Adam Again. While none of these bands broke through to the mainstream, later, more successful CCM bands likely stood on the shoulders of these bands.
Keith Green is probably the most well known pioneer of christian rock, releasing his first album To Those Who Have Ears To Hear, in 1977. He didn't have hit records as such, but it was early days for christian popular music and he was the first musician to successfully make christian music with a professional, pop-song stucture. His popularity was certainly helped too by his friendship with Bob Dylan, who was a big fan of his music.
Dylan himself, converted to christianity in 1979 and released a series of Gospel albums. Around the same time, 2 other famous musicians also converted, Kerry Livgren of Kansas and Dan Peek of America, though none of these conversion could be said to have revolutionized christian music exactly.
In the late 60s, Larry Norman, a man of individualistic christian faith, began revolutionizing christianity through his music, which spoke of some of the dark corners of society and preached a need for change and called for renewed understanding and application of the teachings of Christ. His friend and disciple Randy Stonehill also began recording albums, similarly, but in his own individual way. Though neither man recieved much attention at the time, I don't believe there has been a christian musician of such unique faith, as these men, in the music business since, with exception of Paul "Bono" Hewson of mega-famous rock band U2 and possibly famous singer-songwriter Van Morrison or the Canadian political musician Bruce Cockburn. Larry Norman in particular is now hailed as the father of contemporary christian music.
A quirk occured in 1979 when the British synthesizer pop band After the Fire, had success in the UK with their album Laser Love. The two successful singles from the album now seem like blueprints for later christian pop songs. In "One Rule For You" they defend their right to preach/share their christian beliefs and "Laser Love" is a modernized worship pop song, using cosmic language to describe God. It seems all the more notable, that such songs would be successful in the UK, which generally isn't that receptive to christian music, but it's true that synth-pop was still quite new and novel in 1979 and the messages of the songs might have gone unnoticed. After the Fire were of course, much more well known for their 1982 hit "Der Kommissar" an English version of a song by German musician Falco which supposedly didn't have any christian message.
Bono and U2 can claim to have revolutionized christianity, particularly in the UK. They began recording political music in their homeland Ireland in the late 70s and in their 1981 album October, they added explicit christian spirituality to the songs. Their next album War was a big international hit and their 1987 album The Joshua Tree is thought to be the peak of their career. U2 were hailed as heroes by both christians and those of other beliefs, though many christians havn't accepted them as genuine, Bible-based christians. U2 started a movement among musicians in the 80s which included UK groups The Alarm, Simple Minds, Big Country, The Waterboys, World Party, The Housemartins and The Proclaimers, Australian groups Midnight Oil and INXS and US group The Call.