The ultimate strong man
No one can enter a strong man’s house
to plunder his property
unless he first ties up the strong man.
Then he can plunder his house.
This metaphor works a couple of ways. Satan is strong and cunning and so Christ would not be able to bring souls back to God (thereby plundering the domain of Satan) if Christ had not already asserted mastery over Satan.
But it also works another way, which we see more clearly in a parallel to this chapter in Luke 11:21-26.
When a strong man fully armed guards his palace,
his possessions are safe.
But when one stronger than he
attacks and overcomes him,
he takes away the armor on which he relied
and distributes the spoils.
Whoever is not with me is against me,
and whoever does not gather with me scatters.
When an unclean spirit goes out of someone,
it roams through arid regions searching for rest
but, finding none, it says,
"I shall return to my home from which I came."
But upon returning,
it finds it swept clean and put in order.
Then it goes and brings back seven other spirits
more wicked than itself
who move in and dwell there,
and the last condition of that person
is worse than the first.
Sometimes, especially if we have been progressing in the spiritual and moral life for a long time, we can grow complacent. We may become proud of our willpower, our good habits, and our clear intellect.. We may even think that we are immune to temptation and sin.
Our lives may be "swept clean and put in order", but only the power of our Lord and Savior Jesus Christ can keep us free from the temptations and sin that can slip quickly past our defenses and cause us to stumble.
Christ is the strong man who cannot be overcome. Only in him, with him, and through him can we be safe.
Whoever does not gather with me scatters.
Lord Jesus Christ, son of the living God, be merciful to me - a sinner.