What do you consider to be mental malpractice?
From Miscellaneous Writings by Mary Baker Eddy, page 31-32
Mental malpractice is a bland denial of Truth, and is the antipode of Christian Science. To mentally argue in a manner that can disastrously affect the happiness of a fellow-being—harm him morally, physically, or spiritually—breaks the Golden Rule and subverts the scientific laws of being. This, therefore, is not the use but the abuse of mental treatment, and is mental malpractice. It is needless to say that such a subversion of right is not scientific. Its claim to power is in proportion to the faith in evil, and consequently to the lack of faith in good. Such false faith finds no place in, and receives no aid from, the Principle or the rules of Christian Science; for it denies the grand verity of this Science, namely, that God, good, has all power.
This leaves the individual no alternative but to relinquish his faith in evil, or to argue against his own convictions of good and so destroy his power to be or to do good, because he has no faith in the omnipotence of God, good. He parts with his understanding of good, in order to retain his faith in evil and so succeed with his wrong argument,—if indeed he desires success in this broad road to destruction.