There are many ways in which an exorcist can fail.
Sin can be confessed, if one knows about it. Pride is more elusive from being recognized the more rooted it is in someone. Lord, save me from the sin I do not recognize as sin! If an exorcist is filled with pride, he will not succeed with an exorcism.
One can also fail in the very methods of discernment. Believe it or not, there are a few exorcists, mostly over in Italy, who use the ways of old world divining in order to judge whether or not someone is being harassed by Satan. Here are some of those ways (perhaps you can think of other silliness): (1) Tie a rock to a string and see if, while holding your hand still, it will swing in this direction, or, “significantly”, that way (whatever way that is… Sigh); (2) put drops of oil in the glass of water and see if the oil separates or stays together or mixes with the water; (3) … I could think of others, I suppose – like the misuse of “charismatic gifts” – but I get impatient with such things.
A word needs to be said about exorcisms which fail, not because of any egregious mistake on the part of the exorcist or the unwillingness of the candidate for exorcism, but just because “it doesn’t seem to work.” Days go by. Weeks. Even months or more. Exasperation. People are praying and fasting and keeping up with the sacraments. But no success.
What to do? Give up so that Satan has a victory, at least in the eyes of the exorcist and in the eyes of the candidate for exorcism? That’s not an option.
How about calling in more exorcists so that it’s not so much about the rite as about the “power group”? Nope. Not for that reason, at any rate. Maybe for solidarity and a watchful eye. Two heads are better than one. But as far as the exorcism goes, that may be of no help.
How about reexamining – before weeks and months go by – whether or not the discernment about demonic possession was accurate? Yep. Hurts the ol’ pride, but that would be it. I would give examples, one in particular being catastrophic, but I don’t know enough about that case to comment accurately. So I won’t. There are things, however, that would point to an incorrect discernment: the exorcist agrees with the political/ecclesial outlook of the exceptionally good candidate and all too easily looks upon the would-be possession as a martyrdom, a punishment for being good. Are doctors or psychiatrists held at bay? Is there any disobedience or trying to skirt around the authority of the bishop? Does the exorcist have a need to be important, needed? Although an exorcist may realize that there are no real signs of possession, these can be overlooked in favor of exorcizing that which can’t be exorcized if such things not coming from Satan’s minions, such as voices in one’s head. One might hear the candidate for exorcism having conversations or even arguments between what might be possibly multiple partial personalities created under great duress. But that doesn’t say anything one way or another regarding discernment, does it?
When I was a young and stupid exorcist, I did record part of an exorcism, the horrific, weird groaning and freakish, monstrous noises coming out of the mouth of such a frail young person. Listening to this, it reminded me of hearing magnetic tape recordings played backward. So, I tried that. Yikes! Many voices were going on at the same time, with some in Biblical Hebrew, saying that [...] is coming to judge, or that it’s not time yet, or similar things. But even this, even with the ghastly appearance of the candidate, doesn’t necessarily point to possession, as the human mind can be extraordinarly adept at creating such scenarios as part of a reason to exist in this world. Discernment involves something other than this, or alongside this, doesn’t it?
The failure of the exorcist in any way can mean the failure of the exorcism, and sometimes it can mean that which is worse than a failed exorcism. A prime example:
If exorcists fail to exhort those over whom they’ve done a successful exorcism, so that they might keep up with frequenting the sacraments, and giving themselves to prayer and works of charity, will not Satan return to find the house (i.e., the person) swept clean and in good order, and then get seven other demons to join him in harassing such a person who failed to fill up his house, his own self, with God’s grace and good works? Yep.
That would count as worse than a failed exorcism, wouldn’t it?
Why would an exorcist fail to exhort a person in this way? Because, unfortunately, unless he is very humble, he will be so intent on praising himself for a successful exorcism, that the end of the exorcism, helping someone to have fuller liberty to live their lives before God and man in all goodness and kindness, will be last on the list of things to do, or will not even have made it on the list. Exorcists are urgently called upon to be humble, and to be always in the mode of humble thanksgiving before God. We are never to rejoice that the unclean spirits are subject to us, but that our names are written in heaven, as Jesus said, in His extraordinary goodness and kindness.