Probably without realizing it, the moviemakers were illustrating a spiritual truth

Forbidden Planet (1956) was an early sci-fi film and one that I consider a sci-fi masterpiece, with more significant meaning than almost any other sci-fi.
It begins with a spaceship from Earth traveling to a strange planet where 20 years earlier another spaceship had crashed. Everyone on board had been presumed dead, but recently there had been some rather odd radio signals from this planet, so the crew of this second spaceship went to investigate.
Once they land on the planet, they discover a beautiful palatial villa where a scientist and his beautiful daughter live. Attached to the villa is a gorgeous garden where there are all kinds of tame animals, including ones that are normally savage.
The race of very intelligent beings that had originally inhabited the planet had mysteriously died off, but all of their machinery was still running. The most amazing machine of all was the “thought machine,” through which they could create things by more-or-less wishing them.
The scientist had figured out how to use the thought machine, and it was all very nice in the beginning when he created things like lovely meals and pet tigers. But things got out of control when he became jealous of his daughter’s love for the space captain, and the machine began creating demons from the imaginings of his evil heart and jealous spirit—like an enraged tiger that tried to kill his daughter and the monster that eventually killed the scientist himself.
It seemed that the highly developed civilization that had once existed on the planet had done about the same thing in using monsters to protect it from invaders, but the monsters turned on the people who’d created them and wiped them out too.
Probably without realizing it, the moviemakers were illustrating a spiritual truth. God’s Word teaches that if we entertain a fear, it will come upon us (Job 3:25). So spiritually speaking, those things can happen.
Some people take drugs or flip out in some way, and they slip over the border into the spirit world where the present material world is no longer their reality. Some of them go crazy with schizophrenia or whatnot, and their demons and nightmares and hallucinations become real to them. It starts in their imagination, but once they slip over the border into that spirit world in their mind, it all becomes very real and horrifying, because they don’t have Jesus and His protection.
The Lord says we shouldn’t think about the dark side at all. “Whatever things are true, whatever things are noble, whatever things are just, whatever things are pure, whatever things are lovely, whatever things are of good report, if there is any virtue and if there is anything praiseworthy—meditate on these things” (Philippians 4:8).
Whenever thoughts of evil come to mind, we should call on Jesus for protection. Jesus said, “All authority has been given to Me in Heaven and on Earth” (Matthew 28:18), so if you have Jesus, you’ve got all that power. All the devils of Hell, including Satan himself, are subject to your power because you have the power of Christ. So “resist the Devil and he”—as well as the evil thoughts he inspires—“will flee from you” (James 4:7).
This problem with evil thoughts entered the world in the Garden of Eden, when first Eve and then Adam ate the forbidden fruit of the “tree of knowledge of good and evil” (Genesis 2:16–17; 3:1–6). This movie’s title seems to be a play on words, with that in mind.
Science is sitting at the foot of the tree of the knowledge of good and evil and plucking off its fruit, but the trouble is that some of it’s good but some of it’s bad. The evil imaginations of evil minds can be brought to life by science, and some of them have been. What is about the most evil thing that science has ever created?—The atomic bomb! But now they have created bombs that are many times more powerful than those that wiped out Hiroshima and Nagasaki—horror bombs that could wipe out whole countries!
God says, “Whatever a man sows, that he will also reap” (Galatians 6:7). You can’t create such evil just to use against your enemies, because the inviolable law of the Bible is that the sower is the one who will reap the consequences. Those who have sowed the wind may very well reap the whirlwind (Hosea 8:7). Revelation chapter 18—which seems to be describing a coming nuclear war—says, “In one hour such great riches came to nothing. … Thus with violence the great city Babylon shall be thrown down, and shall not be found anymore” (Revelation 18:17,21).
 The Bible admonishes us, “Keep your heart with all diligence, for out of it spring the issues of life” (Proverbs 4:23). In other words, we need to watch the imaginations of our hearts, lest they turn evil and become realities that can destroy us. This is why we all need Jesus and the Holy Spirit abiding in us, and why we need to fill our hearts and minds with the light of God’s Word. Then we will dwell in the secret place of the Most High, under the shadow of the Almighty, where no evil can befall us (Psalm 91:1,10). ¨