All parents routinely train their children in the faith which they themselves practice; as they themselves were trained. It is in this fashion that all religions survive. Only three world religions, Christianity, Islam and Buddhism are missionary religions. Although Christianity is the religion most often attacked for "indoctrining" (to use your words) children, these parents are doing the same thing that Jewish and Hindu parents do with their own children. They fact that you disagree with their methods (which obviously you do) does not mean they are wrong for doing so. Religious training is part of the nurture which parents provide for their children. If not, the world would be a much less religious place.
I do not agree with many fundamentalist's approach to religious training; in fact much of it disturbs me; still I respect the right of parents to raise their children in their own way, as long as it is not abusive or violent.