My mom, despite having a very strange and motley patchwork of beliefs (Spiritualist, Buddhist, Christian Science) and working as a singer in churches and temples of all sects, decided to send me to a Lutheran school until I was in 6th grade, when I transferred to a public education system.
Her logic was that many people brought up without religion are oftentimes susceptible to being the most dogmatic religious people if the idea of religion is introduced to them at a later age. So rather than planning for me to be Christian my whole life, I was sent to a private school in order to be desensitized to biblical teachings (although my mother never said anything cynical about Christianity until I was much older).
In some ways I see her logic. It's important for people to know about religion and different influences, so that they have some understanding of how communities, religious, social, or political, function before they're old enough to make their own choices. Helping children perceive the world around them, including the biased information thrown at us, is important to building good judgment.
Certainly there's nothing wrong with raising children to be atheists or agnostic. Certainly there should be no uprising against this woman for having decided not to pass down religion to her children.