A: Since your question is primarily concerning a person who suffers from mental illness, I must first advise you that the person in question (whether it is you, or someone else) should see a medical professional as soon as possible for diagnosis and treatment. We are not equipped to lend medical advice...
No matter what our transgressions, there is always a chance for redemption, which can be synonymous with "salvation," as in this passage about Jesus' love towards sinners; and not only redemption, but "eternal rehabilitation." This Urantia Book quote is about the cross of Jesus, and its significance to sinners.
"The cross forever shows that the attitude of Jesus toward sinners was neither condemnation nor condonation, but rather eternal and loving salvation. Jesus is truly a savior in the sense that his life and death do win men over to goodness and righteous survival. Jesus loves men so much that his love awakens the response of love in the human heart. Love is truly contagious and eternally creative. Jesus' death on the cross exemplifies a love which is sufficiently strong and divine to forgive sin and swallow up all evil-doing. Jesus disclosed to this world a higher quality of righteousness than justice—mere technical right and wrong. Divine love does not merely forgive wrongs; it absorbs and actually destroys them. The forgiveness of love utterly transcends the forgiveness of mercy. Mercy sets the guilt of evil-doing to one side; but love destroys forever the sin and all weakness resulting therefrom. Jesus brought a new method of living to Urantia. He taught us not to resist evil but to find through him a goodness which effectually destroys evil. The forgiveness of Jesus is not condonation; it is salvation from condemnation. Salvation does not slight wrongs; it makes them right. True love does not compromise nor condone hate; it destroys it. The love of Jesus is never satisfied with mere forgiveness. The Master's love implies rehabilitation, eternal survival. It is altogether proper to speak of salvation as redemption if you mean this eternal rehabilitation."
God's forgiveness is also forthcoming for our sinful acts:
"...The Father in heaven has forgiven you even before you have thought to ask him..."
As for the second part of your question: There was a time on our planet when this belief that evil spirits could possess the minds of men did have some credibility...even in Jesus' time, there were rebel midwayers still roaming the earth—remnants of the Lucifer rebellion who were able to influence the minds of men—but since the day of Pentecost , over 2000 years ago, when the Spirit of Truth that Jesus promised was poured out upon all flesh, no evil spirit has had the power to affect the minds of mankind.
"The entire group of rebel midwayers is at present held prisoner by order of the Most Highs of Edentia. No more do they roam this world on mischief bent. Regardless of the presence of the Thought Adjusters, the pouring out of the Spirit of Truth upon all flesh forever made it impossible for disloyal spirits of any sort or description ever again to invade even the most feeble of human minds. Since the day of Pentecost there never again can be such a thing as demoniacal possession."
As for the third part of your question: All of us sometimes have the feeling that we are influenced by factors out of our control, and yet, this does not necessarily denote mental illness; however, if a person is convinced that they are "severely mentally ill" it is of great importance that they go to see a medical professional as soon as possible...
And at any time, any person who feels ill—mentally or physically—can turn to prayer as a supplemental means of feeling better:
"Prayer is not a technique for curing real and organic diseases, but it has contributed enormously to the enjoyment of abundant health and to the cure of numerous mental, emotional, and nervous ailments."
Thanks again for writing to us. Please click on the links provided to open the text and best wishes."