I try to be as unbiased and fair to everyone as possible, whether it be politics, religion, etc.
I disapprove of most forms of indoctrination, of course, that is only possible to an extent. Some organizations have no place exploiting biases to use as indoctrination, however. The public school system is one, law enforcement is another.
But that's not the question I'm asking -- how do you determine what's opinion, what's values and what's indoctrination?
You're eventually going to have to teach your children that. Yeah telling a 9-year-old that there is, definitively, "no God" is overboard. But the solution to this problem is not sequestering children away from opinions or subjective interpretations of fact. Too many confuse this with limiting their kid's exposure to information to info that's universally accepted in their culture, or that they personally accept, or whatever. That's still a type of indoctrination.
For the record, I went to public school. I had outspoken Democrats and Republicans for teachers, obviously more of the latter. They sometimes went over the line, but there was no brainwashing. I never had any teachers definitively speak against God and I'm from urban WA; I think your experience was almost certainly an anomaly.