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 embracing the parent's faith.
It can be found in the priest who scolds a woman because her doctor ordered her to go on the pill, because getting pregnant again could kill her, instead of showing compassion first and then trying to see what other options might be.
It can be found in the person who turns away from faith because that faith forbids this or that thing, and then sets out to undermine, criticize, put down and even legally challenge that faith (institution) by setting up legal precedent, and/or laws meant to force religion (and any morality considered undesirable) down a hole somewhere.
True conversion comes with a desire to better oneself. As much as we may desire others to live the same liberating experience, we must take people where they are in their spiritual life. People do not like to be controlled, and not everyone has the same path to take in life. Sometimes you have to go down a slippery path and fall to the bottom in order to rise again, a better person.
Sometimes, the only thing, and the best thing you can do for a person is pray.