What we think is important.
I don’t mean that our opinions about various topics are important. They may or may not be important; but I mean that the content of our thoughts — what we are thinking about in any given moment is important. The millions of thoughts that travel around our six-inch diameter gray matter every day do matter. Those thoughts form our desires and they inform our decisions and guide our actions. It might be true that “you are what you eat” physically, but it’s even more true that we are what we think. How we live is the product of how we think. Our actions are the result of our thoughts. What we think is important.
In his book, God’s Battle Plan for the Mind, David Saxton says,
“Perhaps the best advice I could offer someone who desires to become a stable, godly person of meditation is this: turn off the television and fight the temptation to be an entertainment-dominated person. The wholesale surrender of the mind to the world’s programs and amusements led R. Kent Hughes to bemoan, ‘This cosmic potential of the believer’s mind introduces the great scandal of today’s church: Christians without Christian minds, Christians who do not think Christianly.” 
What are you thinking? In this moment, what is occupying your thoughts? Today, what are your desires and longings?
In Colossians 3, the apostle Paul calls his readers to have their thinking consumed with Christ — to have their attention set on Him and their position with Him. He says it this way:
“Set your mind on the things above, not on the things that are on the earth.” (Col. 3:2)
The verb “set your mind” is a favorite word of Paul’s (23x of the 26x it appears in the NT). It means “to think, to form an opinion, or to have an attitude.” It is an inner disposition. It’s our heart — our desires, longings, motives, thinking, will. It’s to have an inner disposition towards God and Christ.
And as in v. 1 (the word “seek”), this is a present tense — keep thinking (because we are prone to stop). This is a reminder that there is an intimate connection between the way we think and the way we live. We will do what we think. What we think is the way we will live. And if we want to be sanctified in our loneliness, in our fear in the present, anxiety for the future, depression over the past, anger over loss, or bitterness over injustice against us, then our thoughts must change.
Further, we will never change what we do until we change the way we think. And we must not just think, “Stop doing _________.” We must have thoughts focused on “the things above:” our priorities and thoughts need to be aligned with God’s priorities and thoughts. We need to think the way God thinks. “Our feet must be on earth, but our minds must be in heaven.…the practical everyday affairs of life get their direction from Christ in heaven.” [Wiersbe]
To align our thoughts with things above, we must also “not set our minds on things that are on the earth.” Paul is not saying we shouldn’t be concerned as stewards about things on earth. He is not saying the physical world around us is unimportant — Paul is not a gnostic, saying all physical things are bad. But he is rejecting the priority of the world. He is rejecting the morality of the world. He is saying we need to stop acting as if Heaven is temporary and earth is eternal.
We get a hint at what he means when he uses a similar phrase in v. 5 — “what is earthly in you.” There he is talking about the earthly things that need mortifying — sinful activities that have no part in the life of the believer: immorality, impurity, passion, etc. So Paul is saying we need to stop living for the world and all the things the world prioritizes. We need to live for God’s priorities.
And that change in living begins with a change in thinking. And that means we need to feed our minds things that are heavenly and not earthly. And we won’t find what is heavenly on ESPN, Fox News, CNN, HBO, or Netflix. We won’t find that on unseemly websites or in lurid novels. As one theologian noted years ago, “No Christian, however pious, will ever grow [spiritually] if he feeds his mind on trash…” [Gaebelein]
When we struggle with fear, anxiety, loneliness, depression, anger, worry, and a host of other internal sins, it is because — at least in part — we are focusing more on what is earthly and less on what is heavenly. We are thinking more about what we are losing on earth than what we will gain in Glory. We may be feeding ourselves Scripture, but as much as these sins overwhelm us, we aren’t allowing the Scripture to shape our thinking, our desires, and our actions.
So here is one simple test: For every thought or desire, we do well to ask, “is this heavenly or earthly thinking? Is this God-honoring or worldly-informed? Is this life-thinking or dead-thinking?”
What are you thinking?
Is our answer to that question shaped by our identity in Christ and the glorious riches God has for us in Heaven? Let us be so wrapped up in Christ and be so heavenly-minded that we become of greatest good on earth. Let us pursue heavenly desires so we can accomplish God’s purposes for us until we get to Heaven.