"You are what you eat" is a common expression. Our physical bodies certainly use what we eat as energy and raw material for new tissue. But this adage is not entirely true. Jesus says in Mark 7:15-16, "There is nothing that enters a man from outside which can defile him; but the things which come out of him, those are the things that defile a man. If anyone has ears to hear, let him hear!" Jesus is explaining that we are not necessarily what we eat but what we think. Proverbs 23:7 backs Him up: "For as [a man] thinks in his heart, so is he."

Even though we are what we think, we are not always what we think we are. Paul says in Romans 12:3 that a person should not "think of himself more highly than he ought to think." He goes on to say that we should "think soberly," that is, not that we should think little of ourselves but seriously and realistically. After all, we are ambassadors for Christ and kings and priests in training for God's Kingdom. Nevertheless, we still fight that old, sinful nature, so we cannot allow ourselves to be puffed up due to our positions, abilities, gifts, or authority that God has given us.

One of the most important things we do is to think. Our thinking can be profitable or futile. We are—or should be—the masters of our thoughts. We can thus think of good or we can think of evil—the choice is ours. But we cannot think both good and evil thoughts simultaneously anymore than we can travel east and west at the same time. A thought must be all good, for if it contains any evil, it is evil. So we have to choose carefully what to think. Our thoughts are:

righteous or unrighteous,
clean or unclean,
moral or immoral,
honest or dishonest,
pure or impure,
true or untrue,
just or unjust,
good or bad, etc.

In Psalm 119:11, the psalmist says, "Your word I have hidden in my heart, that I might not sin against You." Like a costly treasure, God's Word should be hidden in our hearts, our minds, so that we guard ourselves from sinning against God in thought, word, or deed. We always sin in thought before we sin in word or deed because the things that defile us, as Jesus said, originate inside us. A thief is a thief because he thinks like a thief. A liar is a liar because he thinks like a liar. An adulterer is an adulterer because he thinks like an adulterer. "For as he thinks in his heart, so is he."

God says through the prophet in Isaiah 55:7, "Let the wicked forsake his way, and the unrighteous man his thoughts; let him return to the LORD, and He will have mercy on him. . . ." Forsake can also be translated as "to leave" or "to refuse." We need to refuse to think unrighteous thoughts because unrighteous thoughts will lead to unrighteous or wicked ways. There are only two ways to think: the righteous way and the unrighteous way.

Jesus instructs, "A good tree cannot bear bad fruit, nor can a bad tree bear good fruit" (Matthew 7:18). A person cannot live a righteous life and think unrighteous thoughts. Likewise, one who thinks good thoughts cannot live a bad life. In the same vein, James writes, "No spring yields both salt water and fresh" (James 3:12). No one can live a righteous and unrighteous life at the same time. One can, however, forsake—leave or refuse—his unrighteous thoughts and return to the Eternal, and He will abundantly pardon.

In Isaiah 55:8-9, God describes His own thoughts: "'For My thoughts are not your thoughts, nor are your ways My ways,' says the LORD. 'For as the heavens are higher than the earth, so are My ways higher than your ways, and My thoughts higher than your thoughts.'" Thoughts means "purpose or intentions." When we think unrighteous thoughts, our purposes and intentions are not the same as God's because He never thinks unrighteous thoughts. Ways implies "direction." When we think unrighteous thoughts, they will lead us in the wrong direction, to live a way in opposition to God's.

God describes David as "a man after My own heart," meaning that David had learned to think just like God. He desired his purposes and intentions to be like God's, to walk in the same direction that God did. It should be our goal to have God say this about us, that we are people after His own heart.

Psalm 119:97 reads, "Oh, how I love Your law! It is my meditation all the day." If David authored this psalm, he did not sit around all day with his legs crossed, hands on his knees, and eyes closed, meditating on God's law. He was a king; every day was a busy day. He had to make countless decisions, solve difficult problems, and make crucial judgments every day. This verse means that he thought about God's law and applied it to all his decision-making, problem-solving, and judgment-rendering throughout his day.

A martial arts instructor, wanting to teach his students how to meditate, told them that the first thing they need to do is to empty their minds of all their thoughts. Upon hearing this, a group of a half-dozen or so Protestant students quit his class, saying they were not emptying their minds of all their thoughts because this could open them up to demon-possession. Both the instructor and the students misunderstood what meditation really is. Meditation is simply refined thinking; it is focusing or concentrating on a certain idea.

It would be nice if we could just send all our unrighteous thoughts to a recycle bin and empty it, then open up our minds to pure and righteous concepts. But it is not this easy. The way to get rid of unrighteous thoughts is to bring "every thought into captivity to the obedience of Jesus Christ" (II Corinthians 10:5). This takes meditating or thinking in a focused manner on God's Word and applying it to our life all day long. If we do this, we will have little time or desire for unrighteous thoughts.

Philippians 4:8 contains the apostle Paul's suggestion about the content of our meditation: "Finally, brethren, whatever things are true, whatever things are noble, . . . just, . . . pure, . . . lovely, . . . of good report, if there is any virtue and if there is anything praiseworthy, meditate on these things." He is saying that we have a choice in what we think about, either the good or the evil, so choose to think righteous thoughts because we are what we think.