Have you ever tried to take the air out of a cup?
Probably not. It sounds crazy. Impossible, even. You can’t scoop the air out. You can’t turn the cup upside down and dump it out. It’s air—it’s going to stay in that cup no matter how much you shake things up or flip them around.
But there’s a trick—and once you know the trick, it stops being impossible and starts being laughably easy:
Water.
Just add water.
The trick to getting air out of a cup is to focus on replacing the air, not just removing it. By adding water—or dirt, or chocolate milkshake, or quick-set concrete, whatever’s handy—you can force the air out of the cup by making sure there’s no room for it anymore.
Voilà. Problem solved. Air removed.
The secret to blocking unwelcome thoughts
Have you ever tried to keep certain thoughts out of your mind?
It’s a lot like trying to get the air out of a cup. If your only focus is on getting those thoughts out, you’ll find that they excel at getting right back in. And, in all likelihood, they’ll come back with a vengeance.
When we tell ourselves to stop thinking a particular thought, most of us find it difficult to do anything but think that thought.
Turns out the trick is the same:
Add something.
In the arena of the mind, it might not make the battle laughably easy—but it does make it possible as we try to bring every thought into captivity.
Consider Christ’s warning about demons: “When an unclean spirit goes out of a man, he goes through dry places, seeking rest; and finding none, he says, ‘I will return to my house from which I came.’ And when he comes, he finds it swept and put in order. Then he goes and takes with him seven other spirits more wicked than himself, and they enter and dwell there, and the last state of that man is worse than the first” (Luke 11:24-26).
Different subject; same principle. The demon had been kicked out, but nothing was stopping him from returning—and with company to boot. The metaphorical house he returned to (in this case, a person) was clean, swept—and empty.
Leaving our cups empty means leaving the job unfinished—and easily undone.
So what should we fill our minds with?
When it comes to thoughts, quantity matters
We have options—lots of options—but not all of them are good options. If we’re not careful, we can fill up our minds with things that only make life harder for us. We can start dwelling on even worse thoughts that become even more difficult to get rid of.
So we have to be careful with what we add to our minds. But we’re not left to figure it out through trial and error.
Paul wrote, “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).
It almost sounds too simple. “Just think about good things!” But there are a few things to consider here.
The first is that the human brain can only focus on so many pieces of information at once. The exact number is up for debate—some sources say three or four, some say seven, some say 12—but the point is, it’s not infinite.
That means it’s possible to “push out” thoughts we don’t want by flooding them out with other thoughts. True thoughts. Noble thoughts. Just thoughts. Pure and lovely thoughts. Thoughts about virtuous, praiseworthy things of good report.
If we actively focus on enough of these things, our minds won’t have the capacity to dwell on the thoughts we’re trying to get rid of as we strive to bring every thought into captivity.
Take time to think deeply
The other thing to consider is a specific word Paul used:
Meditate.
Not “think about.” Not “casually entertain.” Meditate. Think deeply, focus intently. Don’t stop at surface-level thoughts like “God is good.” That’s too broad to push out an unwelcome thought—so dig deeper.
Why is God good? What does good even mean? What’s the standard for goodness? How does God embody that standard?
What are some ways you’ve seen God’s goodness in your own life? How are you trying to share that goodness with others? What would happen if [fill in the blank]?
Whatever your topic, go deep. Be specific. The more granular you can be, the more facets you meditate on, the less room you leave in your cup.
Why bring every thought into captivity?
But why should we bother putting out bad thoughts in the first place? Why go through all this effort just to avoid thinking about certain things?
Because your mind is your command center. What you let into your mind—the thoughts you give a home there—will shape who you are.
And so Paul wrote, “The weapons of our warfare are not carnal but mighty in God for pulling down strongholds, casting down arguments and every high thing that exalts itself against the knowledge of God, bringing every thought into captivity to the obedience of Christ, and being ready to punish all disobedience when your obedience is fulfilled” (2 Corinthians 10:4-6).
We are at war against Satan, who would love nothing more than to derail God’s plan for us. One of the ways he tries to do that is by offering us unhealthy things to think about—to obsess over—that drive a wedge between us and our Creator.
This is a war—forgetting that can be fatal. Don’t leave any room for the enemy. When you find yourself thinking about something unhealthy, find the good things. The noble things. The true things. The just things.
Fill up your cup.
For more about protecting your mind, see our article “What Is the Helmet of Salvation?”
Note: Thanks to the many ministers with years of counseling experience who gave their input!