Systematic mind control programming of children against their non-custodial parent is absolutely dangerous. As a mental health professional, I have long worked with children and adults who have suffered from parental alienation as a result of exiting a destructive cult, like Scientology and the Jehovah’s Witnesses (but is a very common practice of all cults). The Jehovah’s Witnesses, for example, have a documented history of efforts to manipulate ex-members by threatening disfellowshipping and legal wrangling to keep children inside the Watchtower group. Children are told that anyone who rejects the Witness lifestyle is dangerous and “part of Satan’s world”–even immediate family members. Watchtower has even published a guide for followers to use when facing a non-believing parent in court to get custody of the children. A PDF of this document can be accessed here. Scientology has their total disconnection policy if someone is declared a Suppressive Person (SP).
Add the component of active negative programming that the child’s parent has betrayed God, or become possessed, or has gone insane. This can cause powerful thought and emotional problems as well. People have had nervous breakdowns, psychotic breaks, suicide attempts, or manifested migraine headaches and other debilitating psychosomatic illnesses.