A while back I was in the confessional at St. Peter's, waiting for the priest to "open the hatch" on my side of the box. Well. An argument ensued on the other side, with harsh whispers insistent enough and loud enough that I had to block my ears. (All I really hae to do is run my fingernail on my veil right where it covers my ears; can't hear anything over that!) Just from the tone of what I had heard, I understood that the penitent was refusing to change a pattern of behavior that led to sin. He (it was clearly a "he") probably didn't see that a pattern of behavior that leads to sin is a sinful pattern of behavior. He just wanted to go to confession and be done with it. It could be a picture of that strange parable in today's Gospel, the one about about a demon who is cast out, but comes back to the tidied house with seven even worse companions.
Sure, the house may get nice and clean, but without a truly "firm purpose of amendment," you haven't replaced evil with a positive good. You've only made room for greater spiritual harm, multiplied by the deceptively comforting thought that the sacrament has taken care of everything.
The first image in today's Gospel, the one about the attacker who overwhelms a "strong man" and takes over his stronghold, gives us the encouragement we need to really wage war against the sin in our life: Jesus has already won the victory!