Fanaticism
Conversion has to happen in the heart, not just in the mind, or it inevitably leads to fanaticism. Fanaticism (religious or non-religious) always leads to some kind of abuse in varying degrees. It might be as silly as looking down on others for wearing open-toed shoes shoes to mass (because that's not modest enough). It might be as extreme as covering up your whole body or baring it all, both of which stem from the mistaken idea that the body is just a sexual thing. It may be found in the parent who "converts" to show to the world how good s/he is, praying and showing off how holy s/he is in public, while making unreasonable demands and spewing abuse on his/her own family in private. It may be found in the control-freak parent who sets a standard of holiness for the whole family that the children cannot realistically follow, and then punishing them for not following the strict monastic-like rule, resulting in children that are exhausted and end up hating instead of...