In 1989 the National Endowment for the Arts funded an exhibition of Andres Serrano's work, which included a photograph of a crucifix submerged in the artist's urine. It was known as the Mapplethorpe exhibition because of the inclusion of Robert Mapplethorpe's work in the funding.
I think that the Serrano work and Christian Rock parallel almost exactly. I understand that those who enjoy and appreciate Christian Rock in almost every instance would not enjoy Serrano's art, but the two, Christian Rock and Serrano, provide an apt comparison. They both portray Christ in a profane setting. Both blaspheme Christ with their medium.
Christian rock is accepted by many Christians and Serrano is not, but I contend that is because Serrano does not appeal to the sensibilities of their fleshly passions. That's why this comparison works so well. Professing Christians have tossed discernment in judging the context and setting of Christian rock. They dial in on the Serrano exhibit. In the former they mistake their passion for some spiritual experience. In the latter, they willingly accept the nature of profanation due to their personal revulsion to urine. To God both former and latter could be characterized by human excrement.
You will not find one explicit verse in Scripture forbidding either Christian Rock or Serrano. You could argue against images of God, but that isn't one that evangelicals and fundamentalists who love Christian Rock have often opposed. So no verses against Serrano. I think this explains some of the emergent art exhibitions and their fondness for presenting Christ in the settings they do, and what we see of portrayals of Jesus commonly on Christian t-shirts.