In all cases we have to make a judgement call in how to use our energies. We cannot as easily change others as we can ourselves, nor are we obligated to put up with abuse.
Based on what you say, it sounds like the best option would be to detach yourself. However, what "detachment" means does not have to be the same for everyone, nor does it have to follow the same manifestation or procedure of occurring.
There is an element of this where we should not force the energy if we don't have to. If someone's preconceived notion of detachment is obliterating any ties, this is different from if the energy is programmed to remove just the negativity. Maybe this would manifest as the abuser leaving the person alone in their room, as opposed to being attached from the roof over their head, too. Also, by focusing first on the removing negative attachments, this would more quickly protect someone who was in danger.
Obviously I cannot fully predict what we will happen, as these situations are subjective. I am mainly writing about achieving a better outcome with our workings, as well as being mindful about our outcomes. This applies more to cases that are more nuanced, but for those that are more severe, this would point towards a full detachment anyway, which could likely be the result if the energy is programmed for the best outcome for you.
If the energetically easiest result of removing the negativity from you involved a change on their behalf, then that is what would happen. Alternatively, if the best option was to get you away somehow, then that would likely happen.
Sure, it would work, but you have to consider how much energy it may take. As I mentioned above, it is usually harder to change others more than ourselves. How likely the individual will change is based on them. If they were open to change somehow, then this could more easily occur. Maybe they become convinced about the pacifistic beliefs from Christianity and this leads them to quit harassing you. This would not totally free them from the self-destructive spiral of Christianity itself, but at least they would leave you alone. That could be one example of a surgical detachment of a negative behavior.