Does it build a bridge to the world (lust of the eyes, the lust of the flesh, the pride of life)?
For your obedience is come abroad unto all men. I am glad therefore on your behalf: but yet I would have you wise unto that which is good, and simple concerning evil. (Romans 16:19)
Most of our learning should be at the feet of godly, separated, knowledgeable (as in, Bible knowledge) believers. Strategies for church growth, child rearing, personal development, worship, the Christian life should not be borrowed from the world. Although beyond the scope of this article, the application of a passage like Psalm 50:16-17 would involve a rejection of any "Biblical" movies produced by Hollywood. There is little basis for entertainment that teaches us more about the worldliness and evil ways of our society.
Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him. For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world. (I John 2:15-16)
What exactly does it mean to love the world? Until recently, the answer to that question was fairly easy. The entertainment, lusts, interests of the ungodly world were forsaken by professing Christians. Now, however, many professing believers, often seeking to justify their own fulfillment of the desires of their flesh (music, television, movies, etc.) deal with verses like this in abstract terms. Unfortunately, most evangelicals today will not be able to concretely apply this verse because so much of the world is already embedded in their hearts.
Consider what Charles Spurgeon wrote about worldly believers in his day: They plead that they may live like worldlings, and my sad answer to them, when they crave for this liberty, is, 'Do it if you dare. It may not do you much hurt, for you are so bad already. Your cravings show how rotten your hearts are. If you have a hungering after such dog's meat, go, dogs, and eat the garbage! Worldly amusements are fit food for mere pretenders and hypocrites. If you were God's children, you would loathe the very thought of the world's evil joys, and your question would not be, 'How far may we be like the world?' but your one cry would be, 'How far can we get away from the world? How much can we come out from it?' Your temptation would be rather to become sternly severe, and ultra-Puritanical in your separation from sin, in such a time as this, than to ask, 'How can I make myself like other men, and act as they do?'" (The Soul-Winner, 1895, p.278)
They did not destroy [disobeyed] the nations, concerning whom the Lord commanded them: but were mingled among the heathen, and learned their works. And they served their idols: which were a snare unto them. (Psalm 106:34-36)
The progression into idolatry begins with unholy mingling with the ungodly. This ought not to be confused with mingling with them for the express purpose (that's right: express, not ancillary!) of proclaiming the Gospel to them, and teaching them the Scriptures and the way of salvation. The progression here is of mingling with them, and learning of their works. Entertainment that teaches the morals and philosophies of the world has no place in the hearts or lives of the disciples of Jesus Christ. Where does your entertainment fit into that analysis?
This applies to a subset of the musical entertainment admitted into the lives of believers today, and bears brief mention here. Most churches have adopted the pop-rock music of the world (please do your research before sending emails about the "piano as a barroom instrument" or "Luther used a barroom tune for A Mighty Fortress" myths) and have declared (contrary to the actual introducers of that music) that music is neutral, and that the profane music and worship of the world can be made pure somehow before a holy God. Only the CCM crowd presents the "music is neutral" argument. Those from whom they receive their musical inspiration certainly do not believe that.
Music is not neutral. In 1 Samuel 16:15-23, David's skilful playing of the harp calmed Saul and caused the evil spirit to depart. Much more could be said about the required solemnity of worship in the Lord's assemblies, as well as the Biblical aim of worship, both of which are set aside in the contemporary worship movement.
The principle of Biblical separation from the world is not coincidentally denied and rejected every major artist within the so-called contemporary Christian music industry. The tenets of I John 2:15-16, James 4:4, II Corinthians 6:14-18, and many other passages of Scripture are virtually ignored in order to justify the acceptance of this kind of music and its corresponding philosophy of worship. Obviously, this only scratches the surface of this issue, and no amount of Scripture will convince those intent on pursuing the desires of their own flesh and a love of the world, but he that hath an ear to hear, let him hear.
Enter not into the path of the wicked, and go not in the way of evil men. Avoid it, pass not by it, turn from it, and pass away. (Proverbs 4:14-15)
The path of Biblical separation means not even seeking to wander close to the philosophies, methods, and practices -- the paths -- of the world, when it comes to the use of our time. Are we building a bridge to the pursuits and entertainment of the world? Better to exercise caution, than to build a bridge over which most will inevitably cross.