Is a person held accountable and taken to task for their disbelief, forsaking prayer, and committing abominations while suffering from religious visual and auditory hallucinations, or is that considered a loss of reason for which they are not held accountable?

If you were overwhelmed and lost your discernment during that period, then you are not held accountable. However, if you were of sound mind and willingly indulged in polytheistic thoughts, then you are accountable. We advise you to treat these hallucinations by consulting trustworthy doctors. Since you have repented and abandoned those thoughts, then through repentance you become like one who has not sinned; as the Prophet, peace and blessings be upon him, said: "The one who repents from sin is like one who has no sin."