What is the meaning behind people claiming to hear voices of God in their heads without anyone else hearing them? Is this a sign of mental illness or possession by an evil spirit?

your Holy Spirit, that is constantly present is part of the trinity as gods representative has been known to talk in some severe cases when asked, but prefers to stay silent 99.9999% of the time in super important cases, like prior to suicide in asking God thoughts on the matter, as it may say ( your not trying to kill yourself but merely the kill the pain as change may alleviate the dire suicide part) as ithe Holy Spirit mostly talks through realization, as your question answers the rest of this as a big yes.

The 63.6 million number are only the diagnosed ones, which one are you ? The diagnosed ones or undiagnosed is the question ? And a serious question, and why prayer is an important resolution that should not be dismissed, as numbing your salvation with drugs is not a cure to your religious salvation, but facing reality is the true answer, not saying you should not take the drugs, just be really careful on your decision, as it may have an eternal outcome attached to it,

believing in Jesus automatically qualifies you for heaven, as Jesus is allowed to clean your slate clean with his cleansing sacrificial blood, and free you from your sin track record as a bonus, so your not doomed yet, just tarnished with hope attached to it. Go and sin no more and enjoy a new outcome and freedom of your enslaved spirit.

Have you ever been humiliated in front of a group of girls and enjoyed it?

Living a life with a foot in based in goodness and the other foot based in evil freedom without morals, will not open the door to wisdom, as dedication and commitment to goodness is needed for wisdom to manifest.

The sin factor opens the door to mental illness and possessions especially with porn and promiscuous behavior, pray for strength to resist such behaviors as in 2018 48 million went to their doctor because of hearing voices whom the doctors are only allowed to prescribe powerful medication, then 3 years later in 2021 that number had increased to 54.7 million, at that same 10% rise rate 2024 should be at 63,6 million, as doctors are not allowed by law to prescribe prayer, unless a patient brings it up, due to mandate created 249 years ago 3 months after we received our civil rights, with treats of losing their degrees and license to operate.

And why Jesus told us to pray, continually, and non-ceasing, as it means of big protection, he went on to also say to seek the counsel of our own Holy Spirit, as a moral compass of sort, crosses are also very important especially above beds,

What happens when you get sick in a country with universal healthcare? What's the process like?