When someone expresses their interpretation or understanding of the way they perceive the world, as mentioned in the previous post, it is likely that they will perceive some (if not a lot of) truth.
So yes, there will be good in what they say. But there will also be things that are ugly or a perversion of good, and we need to recognise these things too. As we get to know God better, as we align our life more with how he wants it to be and as we get to know the Bible more then this stage of engaging with pop culture will come more and more naturally. We'll hear something and alarm bells go off and we see there's something not right here.
Often that's because something that is good has been made into an idol. So when engaging with popular culture we ask questions like 'what is functioning as God here?' 'what's the idol?'. Idols work best when they take something that in itself is good but it's twisted to be given too much importance.
It's very subtle.
If you're trying to attract a fly you use honey and not vinegar, but then when it's landed it's trapped. An idol works in a similar way. It takes something that is good... entices you in... but once you're in there you can become trapped and it becomes no longer good. (Or maybe it's our hearts that do that to it!).
You see a movie and you see the lead character gaining contentment from material wealth and you are trapped into thinking the same thing as most of the west: happiness comes from wealth. So you begin looking for material comfort to bring happiness. But it lets you down.
Or you believe the song when it says that a relationship with the right guy will lead to eternal happiness and so you take what is meant to be good - human relationships - and you turn them into a god. Rather than being something good to be enjoyed, they become a source of pain and brokenness.
Essentially this is a problem of idolatry. Something given in the common grace of God is perceived and we say, rightly, that this is a very good, true and beautiful thing. However, we go wrong when we say that the goodness of it doesn't come from God but rather from itself, the idol. We raise it up to be something that it is not - God - and it does a poor job of it.
Our responsibility in engaging with popular culture is to recognise the good and to liberate it, putting it into it's right context.
We say look at this beautiful thing. It is beautiful isn't it! But it's a lie that it's goodness comes from itself, from this idol. You know as well as I do that no relationship can be perfect and give the satisfaction, contentment and meaning that we want it to give. Let me tell you about the right context.
What's interesting is that most postmoderns do recognise this. They realise that we live in a media saturated world and that from all sides we have different ideas each of which are trying to put their own spin on reality. People know that the media, businesses and all sorts of other sources twist the truth to make you believe a spin on an idea that's helpful to their sales, or whatever. You get one newspaper giving their spin on the story to meet their needs, whilst another presents it in a different way.
So when you say 'can you see that... what this film says will give joy is good, but doesn't in itself really lead to joy and can in fact lead to a lot of problems if our joy is too reliant on it... because it can let us down?', people may be willing to ask those sorts of questions. We can then show them the real source. And we can be confident that because Jesus is the truth, and because Christianity stands up to scrutiny, then the Word will speak for its/himself and testify to the inherent truth.
In re-writing parts of this post I've thought of another helpful question to ask in this area. It's not a new idea, but I thought I'd quickly mention it anyway as it is a useful question to ask when engaging with pop culture.
'What is inconsistent in this person's worldview?'
What I mean is this. If, for example, a film appeals to the commonly held desire for justice, it may be good idea to chat about what is the source of right and wrong, and why justice exists at all. In a world without God, it may be thought to be inconsistent to believe in absolute moral standards, and so an atheistic worldview and a desire for justice may actually be inconsistent. Yet people do naturally have a desire for justice: what's the explanation? The same could be said for many other things.
(Have a read of this provocative article from William Lane Craig on bethinking.org for some more thoughts on this, and have a browse around that website to explore this idea further)