Albert Barnes Commentary Matthew 12:45

"Then goeth he, and taketh with himself seven other spirits more evil than himself, and they enter in and dwell there: and the last state of that man becometh worse than the first. Even so shall it be also unto this evil generation." — Matthew 12:45 (ASV)

Then goeth he, etc. When the evil spirit saw the man's state—dissatisfied with a lonely dwelling in the desert where he could do no evil, envious of the individual's happiness, and supremely bent on evil—he resolved to increase his power of malignant influences and return.

He is therefore depicted as taking seven other spirits, even worse, and returning to his former habitation. The number seven denotes a large but indefinite quantity. It was a favorite number among the Jews, used to signify completeness, perfection, or a sense of fullness (See 1 Samuel 2:5; Revelation 1:4). In this context, it means a number sufficient to completely occupy and harass his soul.

Even so shall it be with this generation. This reveals the scope and purpose of this illustration. The man's condition was a representation of that generation. Much could be done to cure their unbelief and to reform them externally; but the principles of infidelity and wickedness had taken such a firm hold of their minds—as their proper habitation—that they would return, despite all the means used to reform them, and the people would become worse and worse.

And this was literally accomplished. After all the instructions and miracles of the Savior and His apostles; after all that had been done for them by holy men and prophets, and by the judgments and mercies of God; and after all their external, temporary reformations—resembling the temporary departure of an evil spirit from a possessed man—yet so great was their love of wickedness that the nation became worse and worse.

They increased in crime, similar to the sevenfold misery and wretchedness of the man into whose bosom the seven additional evil spirits came. They rejected God's messengers, abused His mercies, crucified His Son, and God delivered their temple, capital, and nation into the hands of the Romans, and consigned thousands of the people to destruction.

It is not proved by this passage that evil spirits actually dwell in deserts. It only proves that this was the opinion of the Jews, that this opinion was drawn from some expressions in the Bible, and that such expressions were sufficiently clear to justify our Savior in drawing an argument from them to confound those who firmly believed that such was the case. Nor is there any absurdity in this opinion.

For

1. There are evil spirits (See Barnes on Matthew 8:33).
2. They must exist in some place.
3. There is as much propriety in their being located on or around our earth as anywhere else.
4. The clear doctrine of the Bible is that many of them have much to do with our world.
5. It is as reasonable that they should commonly dwell in desolate and uninhabited regions as anywhere else.