Source References
Christians should criticize the philosophy they find in, say, movies, if they don't know what the philosophy is about. One really really quick and easy way to tell if they know what they're talking about is to check their references. If they're talking about what Sartre thinks and aren't reading Being and Nothingness, he doesn't know what he's talking about.

One of my professors has an excellent rule--one that got him into Merleau-Ponty and Pollock--if multiple people tell you someone's work is not worth paying attention to, go read them for yourself.