1) Everyone is familiar with the infamous question "If your friends all jumped off a bridge, would you jump too?" that every mother asks. It has become something to invoke a groan, a sigh, or a rolling-of-the-eyes. Yet there is much truth and wisdom to this question! Why should we blindly do something that we
should recognize as harmful - or even evil - just because "everyone else is doing it" (whether family, friend, or stranger; whether Christian or unbeliever). We joke about not being one to "go with the flow", about "standing out from the crowd". Yet how many times are we tempted to do a particular activity, or dress a particular style, or talk a certain way just because it is popular. Now there are many things out there that are perfectly innocent and harmless...but just as many, if not more, that aren't. Christians should live purposefully, as T.M. Moore says, and "think Christianly" as to what we do and why we do it.
We are to live "in the world but not of it." We can, with a good conscience, enjoy pop culture, but we need to be mindful of what is good and edifying (that which will help us to grow in Christ) and that which is not.
2) If I may quote from Moore from chapter 4 of his book Redeeming Pop Culture: A Kingdom Approach....
"Taste is highly personal. This is both the good news and the bad news. That taste is highly personal is good in that each Christian can be encouraged to identify and develop his or her own tastes to the fullest. I don't have to like the same music as my son Casey, and he doesn't have to like mine. We are free to indulge our individual tastes and to be content in the consumption of our own cultural cuisine.
"The bad news is that, besides possibly leading us into cultural activities and enjoyments that do not further our kingdom interests, our individualized tastes can tend to make us cultural snobs, denouncing or at least ignoring every form of popular culture that fails to suit our taste. The problem with this is that, in so doing, we can seem to condemn those for whom such forms are a source of meaning and pleasure. Unless Casey and I can learn to revel in our personal tastes and, at the same time, to respect, take an interest in, and try to understand one another's tastes, we shall have difficulty fulfilling the commandment to love our neighbor as ourselves. Moreover, unless we can manage to get beyond our own tastes to develop new ones--or, at least, to appreciate why others might--we shall have difficulty gaining an entrée for our kingdom mission among those whose tastes range far afield from the eternal purposes that occupy us."
What Moore says even later is that judging something's worth should not come just from personal preference. That question should be answered by questions such as "Is this pleasing to God?", "Does it lead one to a better view of God?", and "Is this something that presents truth and goodness?"