unbalanced mind

The press would later describe the man as 'an insane crank,' 'a dangerous maniac,' and 'a man of unbalanced mind.'

From The Verge ● Mar. 7, 2015

Celsus, a 2nd century anti-Christian polemicist, suggested that the Resurrection was a figment of Mary Magdalene's unbalanced mind.

From Time Magazine Archive

Indeed, he saw pursuit of a single truth as a symptom of an unbalanced mind, tantamount to superstition!

From "Circumference" by Nicholas Nicastro

He was a musician and a man of culture—qualities that, in a prince, must be taken as dangerous indications of an unbalanced mind.

From Essays in Rebellion by Henry W. Nevinson

He was, in all probability, of unbalanced mind, a monomaniac, as most prophets have been; but there is no reason to think that he did not believe in himself, and substantially in what he taught.

From Bible Myths and their Parallels in other Religions Being a Comparison of the Old and New Testament Myths and Miracles with those of the Heathen Nations of Antiquity Considering also their Origin and Meaning by T. W. Doane