Those who have a mental illness making them totally unable to know right from wrong, would need a healing, and of course, God would not refuse to heal one unable to choose Him...
Far more likely, is that the mental illness started via rejection of Jesus, and progressed more and more, like a 'reprobate mind'. Mental imbalance caused by chosen sin, chosen rebellion against God is often talked about in the Bible, as in Romans 2...
Also see Ephesians 4:17-19:
...walk not as other gentiles walk, in the vanity of mind, Having the understanding darkened, being alienated from the life of God through the ignorance that is in them, because of the blindness of their heart... who being past feeling, have given themselves over unto lasciviousness to work all uncleanness with greediness.
That passage well describes the insanity, as found in Satanists, witches, and in all who reject Jesus for some other god.
The vanity of mind means that thoughts are totally worthless. They do not have thoughts that are productive to their spirit, they do not accomplish any spiritual good with their minds.
The understanding is darkened making it like being in a dark room, and what is apparent, if the lights had been on, is totally missed due to the darkness of their minds.
They also are said to be alienated from the life of God. This means that they the blindness means separation, alienation, estrangement from God. God is light, and in Him is no darkness, so if some walk in darkness, cannot see, then, God is not walking with them, and the life and strength, the wisdom and discernment, that would come with a walking with God is absent from those who are spiritually blind.
The passage above also speaks of the ignorance that is in them. There is a worldly knowledge, that some brag upon, with degrees, and doctorates, and proof of much study. Yet, if one is spiritually blind, they are void of real knowledge of the eternal, and they are ignorant despite the degrees and titles.
The passage speaks also of being past feeling. This refers to an emotional breakdown in the person. They do not feel compassion for the sinner, for the weak, for the hurting. They can do immense harm and hurt to people, be insulting and abusive with ease, for there is not the emotion of guilt, shame, and remorse, as there is in people who walk in the light of Gods grace and mercy.
The passage mentions, that spiritually blind people, also have given themselves over unto lasciviousness. Lasciviousness is not always a thing that is sin of itself, but it is the deed that makes one weaker, and leads to sin. So to purposely do things that make one too weak to avoid sins, is lasciviousness. The spiritually blind do not realize that this deed or action, may not be sin, but if they do it, their weakness being increased by such, is going to lead them into things that are definitely sinful. Therefore, willful lasciviousness is sinful. The spiritually blind, not seeing the danger in the path, travel it and then wonder how they were so weak they sinned.
The spiritually blind, finally get to the place where they work all uncleanness. This refers to the things that all of us know are sinful., The spiritually blind, in this final stage of the blindness, have become so depraved due to the long time of darkness, that they sin horrible, shameful sins, not realizing that they are the ones in darkness, and others see the shame of such sins, in better detail, for they are in the light.
These shameful, unclean sins, are done with greediness, we are told. The desire to gain, the desire for carnal mammon, the desire to prosper in earthly things, becomes their motivation, instead of the desire for heavenly approval and reward.
Yes, mental illness is a common cause, probably the main cause of satanic worship, & witchcraft rejection of the true God. One has to have 'vanity of mind' and 'ignorance' etc... to make that kind of choice. After that choice, they mind progressively becomes more and more ignorant and perverted. Many Satanists end in jail or dead, for stupid crimes... Charles Manson, etc...
The one who drove into the ten commandments statue was doing the bidding of that evil voice of a devil, and never fully considered the consequences, or how stupid and crazy the obedience to that devil's voice was...