I'm curious... How can you go to a rock concert and make devil signs with a clean conscience? I'm assuming it's Christian rock? I gave up all forms of blasphemous music.
To answer your question, 1 Corinthians 9:19-23. And, no, it is not Christian rock. I am speaking of bands like Metallica, Megadeth, Ozzy Osbourne, Godsmack, Disturbed, Lynyrd Skynyrd, Poison, and various other heavy metal, hard rock, classic/southern rock, and hair bands. I am an old school headbanger who grew up listening to and loving my secular rock music. Nowadays I still listen to all of this music, along with Christian music. too. I also play the music on guitar.
Jesus hung out with blue collar workers and hookers. How else are we supposed to reach the lost if we do not venture to where the lost are? This is also part of the reason why I am involved with the Disciple Christian Motorcycle Club. The DCMC rides with the Warlocks, Outlaws, and various other 1% MCs. You'd be surprised of the power of the Christian influence when inserted into that kind of scenario. We're all sinners, brother.
And with regard to "devil signs," I must respectfully say that is incorrect. Well, incorrect depending on usage, that is. No different than a swastika being used for good or evil. I would encourage you to check out
http://en.wikipedia.org/wiki/Sign_of_the_horns and
http://en.wikipedia.org/wiki/Evil_eye. The evil eye is in the Old Testament. In the context that rockers use it, it simply means rock 'n' roll, just like the cross means Christianity. Of course, I'm sure you're aware that most all of our Christian symbols, holidays, customs, etc. came from paganism, right?
http://www.seiyaku.com/customs/pagan-symbols.html Again, it's all in the usage and intent.
Of course, as Romans 14:14 states, if this stuff is unclean to you then it is. However, the same does not hold true for me.
\m/