rationalskepticism.org

Making two big assumptions, that Christianity is true and we have good reasons to believe, I would still be extremely hesitant to teach children the evil and wicked preachments that form part of the Christian doctrine. Furthermore, as the Christian position is that those who have not heard the good news are not held accountable for their lack of belief the most moral position would be to keep quiet about it and let God reveal himself to the children as he so chooses.

So the answer to your question is no, a secular education is not a form of child abuse.