Consider the egg. A study of divine design in both variety and symmetry, it anticipates growth and change, and within the sturdy shell resides the very stuff of life. Sturdy, but not indestructible, it must be guarded carefully because the egg faces danger.
Now consider that your mind is like an egg—amazing, resilient, but not indestructible. A young mind anticipates growth and change because it is impressionable. Anyone who tells you that you don't need to guard your mind is either a fool or wants to sell you something.
In the last 20 years science has studied and mapped the human brain, but God long ago mapped the mind. That map is in the Bible, which provides instructions on the proper care and feeding of your mind, the heart of your existence.
Here is what Proverbs 4:23-27 Proverbs 4:23-27  Keep your heart with all diligence; for out of it are the issues of life.
 Put away from you a fraudulent mouth, and perverse lips put far from you.
 Let your eyes look right on, and let your eyelids look straight before you.
 Ponder the path of your feet, and let all your ways be established.
 Turn not to the right hand nor to the left: remove your foot from evil.
American King James Version×says: "Keep your heart with all diligence, for out of it spring the issues of life. Put away from you a deceitful mouth, and put perverse lips far from you. Let your eyes look straight ahead, and your eyelids look right before you. Ponder the path of your feet, and let all your ways be established. Do not turn to the right or the left; remove your foot from evil."
Keeping your heart, guarding your mind—against what and how?
Imagine this. The egg has foes that seek to break it, fry, scramble, boil and rot it. Your mind has adversaries also. Envision mental battles raging in and around your head. Each of your mind's enemies tries to control, deceive, corrupt and pollute it. Forewarned is forearmed.
Battle One: Your mind vs. the demonic spirit world
The popular, head-in-the-sand opinion today—even in some mainline Christian churches—claims that the devil is a myth. But this is not true. Think of this: Satan's greatest freedom to do evil occurs when no one believes he exists.
Satan and his demons were once holy angels. But they chose the way of evil, and now they want to get into your head. But your young and beautiful mind is yours and God's, not theirs.
The devil transmits dark and depraved moods, attitudes and impulses. As "the prince of the power of the air," he is the spirit being working mental, emotional and spiritual corruption in people's minds to lead them into wrong thoughts and active disobedience (Ephesians 2:2 Ephesians 2:2Wherein in time past you walked according to the course of this world, according to the prince of the power of the air, the spirit that now works in the children of disobedience:
American King James Version×). Beware and delete thoughts of selfish lust, rebellion, brooding anger, violent hatred and any other mind-set that violates God's perfect law of love.
Satan worship and witchcraft are seriously growing movements today. Fortunately, some churches have started raising objections by not celebrating the ancient, pagan holiday of Halloween—a day closely related to demons.
Demonic religion appears harmless because horror films with wizards and witches and vampire-slaying TV shows desensitize our minds to the actual danger. Avoid such entertainment, books, magazines, organizations and Web sites. Satan uses them to promote wider acceptance of evil.
Resistance is vital (James 4:7 James 4:7Submit yourselves therefore to God. Resist the devil, and he will flee from you.
American King James Version×). Yield your mind to God and good. Be watchful. As mother Eve misperceived in the Garden of Eden, the devil is a subtle adversary.
Battle Two:Your mind vs. Hollywood
Do you think the motion picture and television industry is concerned about improving your mental and moral health? Do you think that constantly watching scenes of violence and sex has no negative effect on your mind? Think again.
The average American child has logged as many hours watching television by age 6 as he or she will spend in college classes to earn a bachelor's degree, and will spend about as much time in front of the screen as in class for the next 12 years.
TV and movies affect our minds. Numerous studies in America, Australia and elsewhere have established that media violence increases social violence (http://interact.uoregon.edu and http://interact.uoregon.edu). Viewing illicit, electronic media sex and violent programming desensitizes our minds to the sanctity of life and the sanctity of monogamous, heterosexual marriage and family.
What we feed our minds becomes our thoughts just as surely as "out of the abundance of the heart the mouth speaks" (Matthew 12:34 Matthew 12:34O generation of vipers, how can you, being evil, speak good things? for out of the abundance of the heart the mouth speaks.
American King James Version×). We must watch what we watch—meaning beware of negative, electronic peer pressure. Pick films and programs of redeeming value. Reject the glorification of sin, explicit sex and violence.
Battle Three:Your mind vs. the Internet
Never in the history of man has so much pornography been displayed before so many. The Internet as a tool of research can also be the digital line to destruction. To view Internet or printed porn is to commit adultery in the mind. Then the pornography controls the mind, jades the emotions and erodes the moral fiber.
Violent or sexually explicit video games are not healthy for young adult minds seeking the truth—or for any others either. The lure of such gaming is its mentally engaging interactivity and the emotional, adrenal rush caused by the graphic violence. Once again, intense emotional desensitizing takes place, weakening the moral mind.
Use the Internet wisely. Don't let it addict you. Stay away from pornography—anywhere! Play video games sparingly and choose only those that are not morally corrupting.
Battle Four:Your mind vs. university
You mean to tell me that school is messing with my head, too? Unfortunately, yes, even down into the primary grades.
Universities have traditionally been the think tanks of society. This could be a good thing—if the professors were guided by values drawn from the Ten Commandments and a belief in God. Regrettably, this has rarely been the case even when your parents went to college.
Today in most state and private universities, the Bible and those who even claim to believe it are singled out for intellectual and social ridicule. The predominant philosophy of evolutionary, secular humanism is, in essence, modern education's religion. The professors of that mind-set are the wise men, and unquestioning students are the followers.
Your mission is to walk those halls of academia for about four years, assimilate specific, useful knowledge and exit with your faith, that is, your mind, intact. Be thoughtful—"keep your heart with all diligence." The in-your-face bumper sticker says, "Question Authority." So question theirs.
There is strength in numbers. Find others of like mind to yours and encourage each other in clear thinking. Find good, sound-minded mentors to provide you with truth and reality checks.
Battle Five:Your mind vs. yourself
In a paraphrase of the Scottish poet Robert Burns: "O would some Power the gift to give us, / to see ourselves as others see us! / It would from many a blunder free us, / and foolish notion . . ." ("To a Louse," www.robertburns.org/works/97.html).
The human mind with human nature proves self-focused and deceptive. "The heart is deceitful above all things, and desperately wicked; who can know it?" (Jeremiah 17:9 Jeremiah 17:9The heart is deceitful above all things, and desperately wicked: who can know it?
American King James Version×).
Imagine that—your own mind plays selfish tricks on you! So the hardest person to be honest with is yourself. The popular philosophy of today's schools is to teach students to develop self-esteem, to learn to love themselves. God's got news for us: We already love ourselves! The challenge is to learn to love God with all our heart, soul and mind, and to love our neighbor as ourselves (Matthew 22:36-40 Matthew 22:36-40  Master, which is the great commandment in the law?
 Jesus said to him, You shall love the Lord your God with all your heart, and with all your soul, and with all your mind.
 This is the first and great commandment.
 And the second is like to it, You shall love your neighbor as yourself.
 On these two commandments hang all the law and the prophets.
American King James Version×).
Let's give the devil his due. The unseen ruler of this world manipulates our innate selfishness, twisting our own minds around to think, say and do evil. This is what your mind is up against. How can you stop him and win those mental battles?
The prescription is the basis of a true Christian life. Pray daily. Read the Bible regularly. Do what is right. Think about God, others and the truly good things of life.
"Finally," as Philippians 4:8 Philippians 4:8Finally, brothers, whatever things are true, whatever things are honest, whatever things are just, whatever things are pure, whatever things are lovely, whatever things are of good report; if there be any virtue, and if there be any praise, think on these things.
American King James Version×;tells us, "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." VT