If I meant child abuse, I'd have said it, because I do not lie, equivocate, or hide the truth.
indoctrinate
/ɪnˈdɒktrɪˌneɪt/
verb (transitive)
1. to teach (a person or group of people) systematically to accept doctrines, especially uncritically.
2. (rare) to impart learning to; instruct
I stand by that usage. It is not slander, slur, insult, or anything else. It is purely descriptive of the behavior I have observed. And I noted material reasons why it rises to the level of 'uncritically' or 'systematic'. If I saw deviation from the faith of the parents in young children, then I would withdraw that description. However, I don't see a statistically representative portion of Christian or Islamic households with children of the opposite faith. (one of many possible combination examples)
This is quite different from my household. I don't/will not systematically instruct my child to be an atheist. He is simply unaware of things like the concept of god(s). He will discover them in due time, and he may choose one if he wishes. My household is de facto 'atheist' in that no gods are actively worshipped here. There is no need for an atheist doctrine, it is my son's natural unaltered state.
If you feel that use of 'indoctrinate' is not valid as a descriptor, I do not know a word I can substitute it with to show a systematic instruction of doctrine, without critical evaluation. It is what it is.
I can't promise to be fluffy and cuddly, but I do promise to be honest in this venue.