The basic point of the article seems to be that whatever cultural things the world is buying into, Christians should avoid simply to avoid the appearance of being worldly. I would say that if you need to abstain from these things to set yourself apart from the world for God, you aren't living His abundant life! The mark of a Christian isn't legalistically avoiding behavior that could be perceived as "worldly" or "unsavory", it's a dynamic, life-changing relationship with Jesus Christ. That should be the overarching thing others see in you, and as long as you have it at the core of who you are and what you do, I would abstain from defining too many universal standards of how Christians should dress, act, or live (besides the standard of Christ).
If Christians actively shun "worldly" behavior and lifestyles, how far do you take it in the name of avoiding any association with the world? No secular music? No watching sitcoms? What the author suggests would basically make the application of Christian morality a slave to what the world does, or rather does not do, whereas I believe it should come from a relationship with Christ. Indeed, it sounds like the opposite of what Paul talks about in 1 Corinthians 9:
Though I am free and belong to no man, I make myself a slave to everyone, to win as many as possible. To the Jews I become like a Jew, to win the Jews. To those under the law I become like one under the law (though I myself am not under the law). To those not having the law I become like one not having the law (though I am not free from God's law but am under Christ's law), so as to win those not having the law. To the weak I become weak, to win the weak. I have become all things to all men so that by all possible means I might save some.If by becoming more like the world we can win the world to Christ, good! The last thing we as Christians want is to retreat into a cultural bubble that's impermeable to nonbelievers by virtue of removedness--I don't think this is what Paul meant by being "set apart" for the gospel. Bryan, one of my summer project friends who was living the kind of life that would make a fundamentalist cry until accepting Christ less than a year ago, said that this Christian rejection of all things worldly was alienating. "I definitely thought it was alienating because that kind of culture seems incredibly boring. It made me think that religion has its place in society but that those people take it too seriously. Christians of that culture were a major part of the intellectual wall I was putting against submitting my life to Christ." Paul's challenge is not to remove ourselves as far from worldly culture as possible, but to see it as a bridge, a way of reaching people for Christ rather than walling ourselves off.
But, though secondary to living out our relationship with God, avoiding being a stumbling block should be a concern. On the very next page after 1 Corinthians 9 in chapter 10, he tells us to give up our freedom as believers for the sake of other peoples' consciences. "Everything is permissible"--but not everything is beneficial. I certainly understand where the author is coming from about the power of symbols, having listened to a most thorough speaker on the subject in a discussion group at the U. And avoiding symbolic association with evil should still be a concern.
How do we reconcile this with "becoming like one not having the law so as to win those not having the law"? Once again I think Paul hits the nail right on the head in the same chapter: "So whether you eat or drink or whatever you do, do it to the glory of God." The difference is one of intent; in everything we do, the goal should be showing off the glory of God, not simply satisfying ourselves or showcasing our individuality and beliefs or whatever as the world would have us do. I think this is the key difference that should "set us apart" for the gospel--not so much our specific behavior as the heart behind it. One other thing to note is that Paul emphasizes having what you do be to the glory of God--not what you do not do. Bryan added that in instructing each other how to live we should avoid being too negative. "I started to come around when I saw the things Jon and Tom [my neighbors who prayed with me to accept Christ] did, not the things they didn't do. I think that fundamentalists will often focus on what they shouldn't do rather than what they should do. The more important thing for non believers is seeing how much joy you have from serving Jesus."
Of course, how we reveal the glory of God in whatever we do is a lifelong struggle best left to trusting in God's wisdom. If you are glorifying yourself more than God in something, if you can't seem to give it up to Him, then perhaps it really would be best to abstain. But someone more mature in the faith might be able to bring God glory in ways that you can't, so what is not permissible for you might be for him/her. And some things can never be glorifying to God; anything the Bible commands against, for instance. For other things, remember that Christianity is a relationship with God, and like in any other relationship you want to avoid doing things that hurt the other person. For example, as you may know I enjoy listening to heavy metal music quite a bit, but I try to avoid making "metal horns" with my hands because of their Satanic connotations--both in public to avoid making others stumble, and alone simply because I feel like it's hurtful to God.
So, I should wrap this up. I believe that the "abundant life" is lived from the inside out, not the outside in. The focus should be on what's in the heart that only God sees, though this should certainly affect the outside that others see. We're called to be missional and reach out to the world, overcoming evil more by the love of Christ in our hearts than by avoiding behaviors that can be perceived as worldly (though for us the Christian life might include this). I'd like to call back to a recent post of mine citing The Screwtape Letters in describing dancing, music, and so many other elements of modern culture as spiritual "raw material". If they are currently being used by the world as strongholds aginst the gospel, should we simply let the world have them or should we fight to reclaim them and use them as venues to win those inside them to Christ? How knowing God changes your outward life is different for everyone, but it should always be unmistakeable.