This is the correct answer.

Matthew 12:43 is Jesus description of what happens when an evil spirit is exorcised or cast out from a non-believer. Eventually it will return to that person and attempt to enter them again.

If they find the ‘house’ “empty” they will move back into their “former house”, and invite many other unclean spirits, more wicked than the first, and they also will enter the person.

This is Jesus describing the fate of a person who still rejects Jesus and therefore doesn’t have the indwelling Holy Spirit- their house remains empty.

I think this is an example of Jesus speaking to believers, and not everyone, because it would be hard to understand the symbolism He is using.

He doesn’t say, but He implies, that if the unclean spirit returns and finds the house is occupied [by the Holy Spirit] because the person now follows Jesus, the unclean spirits will not be allowed to re-enter that person.