However, in the following passage, we see that they could not rest as they were busy sweeping their own places clean but it just made a space for more evil and self effort.
"When an unclean spirit comes out of a man, it roams through waterless places looking for rest but doesn't find any. Then it says, 'I'll go back to my house that I came from.' And returning, it finds the house vacant, swept, and put in order. Then off it goes and brings with it seven other spirits more evil than itself, and they enter and settle down there. As a result, that man's last condition is worse than the first. That's how it will also be with this evil generation."
(Matthew 12:43-45 HCSB)
I find it interesting that so many evangelicals, especially Pentecostals, make Matt 12:43-45 about demonic possession when it is clearly about self righteous religion. That is the focus that Jesus was speaking about with the evil generation. They were trying to overcome death by religious effort. God had declared humanity good in Genesis 1:31 and Jesus was willing to die to prove it by being resurrected from the dead. Faith in the resurrection brings peace with Father God, and transforms the heart with love. This is why it is so important to present the pristine gospel that Paul and the first century saints proclaimed. It is also important to realize that when Jesus spoke of "this generation," he was speaking of the generation alive at his first coming.