"When the unclean spirit has gone out of a man, he passes through waterless 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 brings seven other spirits more evil than himself, and they enter and dwell there; and the last state of that man becomes worse than the first." (Luke 11:24-26)
“Nature abhors a vacuum.” The origin of the saying is ascribed to Aristotle, who explained the operation of a water pump by suggesting that the vacuum draws up the water. He wasn’t quite correct, since a vacuum is nothing, and nothing can’t do anything. In 1643 Evangelista Torricelli showed that it was atmospheric pressure that forced the liquid up in a vacuum tube; this was the invention of the barometer.
But the “vacuum principle” is still useful, whether or not we understand the physics of it. We sweep our carpets, seal jars of canned tomatoes, or sip lemonade through a straw knowing that if a vacuum is “created” something will try to flow in to take its place. And the principle extends to realms other than the behavior of physical substances. A vacant building draws vandals and arsonists; the plain side of a car in the railroad yards attracts “taggers” and their bold graffiti. And, as Jesus pointed out, a mind cleansed of demonic influence is soon invaded by influences even more demonic than the original, if nothing positive fills the void.
It’s not enough to simply try to rid ourselves of negative thoughts, dysfunctional patterns, harmful habits or addictions, and other “demons” that have a detrimental effect on our quality of life — not to mention the influence of genuinely demonic spiritual forces. The law of the vacuum suggests that these destructive factors will resurface with greater power unless a resisting force has replaced them.
It’s important, then, to exchange hurtful attitudes, warped beliefs and destructive behavior patterns with new thoughts and actions that tend toward what is healthy and good. The apostle Paul illustrates the “vacuum principle” this way:
Therefore, putting away falsehood, let every one speak the truth with his neighbor, for we are members one of another. Be angry but do not sin; do not let the sun go down on your anger, and give no opportunity to the devil. Let the thief no longer steal, but rather let him labor, doing honest work with his hands, so that he may be able to give to those in need. Let no evil talk come out of your mouths, but only such as is good for edifying, as fits the occasion, that it may impart grace to those who hear. And do not grieve the Holy Spirit of God, in whom you were sealed for the day of redemption. Let all bitterness and wrath and anger and clamor and slander be put away from you, with all malice, and be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you. (Ephesians 4:25-32).
In other words, we don’t just give up devious ways, but make the intentional effort to be truthful. We don’t just stop avoiding work or trying to get by at the expense of others; we apply ourselves to earning what we need to assist others who need help. We don’t just quit malicious or vulgar talk; instead, we learn to steer our conversation toward that which encourages and builds up other people. The “pressure” from the healthy replacement behavior helps to keep the old ways from returning. Ultimately, as Paul’s words suggest, it’s the Holy Spirit who must replace our self-seeking tendencies, or those “demons” will only come back to grieve Him, and us.