Parable of the Empty House -- taken from Jesus Christ and the Christian Life: Vignettes of Truth
When the unclean spirit has gone out of a man, it passes through waterless places seeking rest, but it finds none. Then it says, "I will return to my house from which I came." And when it comes it finds it empty, swept, and put in order. Then it goes and brings with it seven other spirits more evil than itself, and they enter and dwell there; and the last state of that man becomes worse than the first.
Here, vividly if grimly, is dramatized the peril of the uncommitted life, of one who may have had a genuine religious experience of forgiveness and deliverance but who does not follow it up with the positive acts and discipline of discipleship. The cleaned house needs to be occupied by the Holy Spirit.
I think this is an answer to the discussion I had recently about why "just being a good person" isn't enough. If your house is empty, who knows what will take up residence. If you do not know where you stand, you open yourself to drifting without purpose and conviction. Who knows what 'demons' will 'possess' you. Drug addictions, workaholism, sex addition, depression,... there are lots of demons we employ when our lives are empty and without purpose.