The most common form of spiritual abuse is not the blood-dripping, baby-eating cult of legend. Any and all religions can be and are used as societal enforcers, to prevent freedom of thought which might lead to nonconformity and divisiveness. This is a form of spiritual abuse.
The best-known example of spiritual abuse that will be familiar to most people reading this is the concept of Catholic guilt. The Roman Catholic Church has declared a great many activities or experiences to be sins, further dividing these into mortal and venial sins. A basic understanding of the doctrine is required for eligibility to take Holy Communion, so children as young as five are educated in the precepts and expected to memorise the catechism. Even at the lowest introductory level, these lessons include a list of sins for which souls are lost. At such an early age, warnings about hell and the sufferings of the damned can make a very lasting impression. The list of sins does not stop at such obvious things as theft or bearing false witness, but includes basic human experiences such as masturbation and biologically-hardwired inclinations such as homosexuality. Many areas of intellectual inquiry are also forbidden.
The list of sins may seem overwhelming to a young person. who may develop a kind of obsessive-compulsive disorder as a result; fearing to think, speak or act without making certain that a sin is not being committed. The practice of confession, without which one is barred from Communion, reinforces for many a feeling of being enslaved or controlled. It is, in fact, a form of mind control.
Without multiplicity even entering the picture, one can easily see why young Catholics sometimes fall prey to feelings of extreme unworthiness which they may seek to alleviate through so-called eating disorders or self-harm. Even as recently as the early 20th century, the child visionaries of Fatima were doing what they called making sacrifices to save sinners from hell, such as going without food or water and wearing rough cords under their clothing. These were perfectly acceptable methods of spiritual discipline in former times as well as today; the canonisation process for those children is well under way.
By no means are these things limited to the Catholic church; analogous experiences can be found throughout Christianity, particularly evangelical fundamentalism.
Dissociation at one time meant the disowning of feelings or desires which were not consistent with the self one wished to be, or to present to others. The theory was that if there were a sufficient number of these dissociated-off bits, they might coalesce into a second self. Common sense dictates that while much of Catholic teaching concerning grace, service to others, etc., may be valid, much of its doctrine is outdated rubbish. Recognising this fact may be a source of intensive Catholic guilt in and of itself. It is possible that some young people split their consciousness in two in order to participate in life in a sensible, realistic way while at the same time appeasing the Catholic self.
Note that many American Catholics do not nowadays take Church doctrine in many matters seriously enough to cause the level of guilt described here.