I work in edtech with a bunch of former teachers, and this is absolutely untrue. Many elementary and middle school teachers see part of their role (regardless of the subject they're officially teaching) as being to teach morals to their students, and the morality that they choose to teach is every bit as subjective as the morality that comes out of a religion.
And if it's not their teachers teaching them morals, then it's their parents. You can't raise a child without intentionally or unintentionally instilling in them your own value system.
The biggest factor in whether someone feels that something is "indoctrination" isn't whether it originates from a religion but whether they agree with the principles being taught.
> There is still school etc, but removing religious indoctrination doesn't add anything else, its just less indoctrination overall.
I should probably have clarified it in the first bit that I meant that the kids weren't told anything about religion, not that the kids aren't told anything at all. My point is that there is no indoctrination required to raise a kid without religion, it is the natural state. I and most people I grew up with were raised that way, religion was stories we read about in school, not some magical thing.
If that is what you mean then I'm pretty sure that even religious homes teaches secular values.
The teachers generally push an empathy based approach to morality, which is absolutely not subjective.
Adopting empathy can cause a number of objective moral pronouncements on a good foundation.
I will take empathy based moral pronouncements over “the bible says so” any day of the week.
What is secular indoctrination? Kids who grow up without a religion doesn't get told anything, all you have to do is to not indoctrinate the kid into a religion.
There is still school etc, but removing religious indoctrination doesn't add anything else, its just less indoctrination overall.