Can you quote pieces of movies? Can you sing along with the radio on practically every song? How does your movie knowledge compare with your knowledge of Scripture? How often do you quote from God's Word? How often do you sing hymns or spiritual songs? Are your friends mainly Christians, or are they people of the world?
The things we allow into our life are the things we dwell on. Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good report; if there be any virtue, and if there be any praise, think on these things. -Philippians 4:8 What knids of thoughts are you having when you watch a movie, listen to the radio, or even read a book? I'm not saying they are all bad, but lots of them have at least some questionable content. These are the things on which we are allowing ourselves to meditate. It only stands to reason that if we are meditating on questionable things, then we aren't meditating on the things we should. What do you tend to talk about with your friends? Matthew12:34 - ...for out of the abundance of the heart the mouth speaketh. This is a good indiation of what our hearts are thinking.
Is it wrong to watch a movie or television, listen to the radio, read a book, or whatever else you do for entertainment? No, it doesn't have to be. We are to diligently guard our heart against the wiles of Satan. Proverbs 4:23 - Keep thy heart with all diligence; for out of it are the issues of life. Satan has blatantly satuurated our entertainment, and if we're not careful, it is no longer wholesome. It is no longer wholesome if we have to rationalize it in any way. "Just ignore the _____." You can fill in the blank with profanity, violence, sex, nudity, bad attitudes, immodest clothing, disrespect, etc. All Satan needs is a single foothold, and that's what these are.
We are to take captive every thought we have and make it obedient to Christ. II Corinthians 10:4 - Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ. We can't do that if we are filling our hearts with worldly ideas. We will reap what we sow. Galatians 6:7-8 - Be not deceived; God is not mocked: for whatsoever a man soweth, that shall he also reap. For he that soweth to his flesh shall of the flesh reap corruption; but he that soweth to the Spirit shall of the Spirit reap life everlasting. What will you reap?