Apparently, she wasn't a teacher but a "pastoral care assistant", so I guess her impact on curriculum activity was limited although I'd agree it's a potential factor.
However, the comments she made on FB were in regard to the school her son went to, not the one she worked at. Her son's school is a Christian school. Unless the comments promoted hatred, someone should not lose their job at a completely different establishment, for their views on the delivery of religious values in the religious school that her religious son attends.
The reason that she's drawn opprobrium on these boards is because she's a Christian, and anti-Christianity is acceptable in many left wing circles in a way that criticism of other religions is absent. But let's look at what Skyscraper and Plank have said here. Huge numbers of traditionally sexually conservative families in Asian communities, such as Sikhs, Hindus and Muslims, also do not want liberal sexual values taught to their kids at school. According to Sky and Plank, those people shouldn't have kids.
This is only a short step from telling people they shouldn't have kids because of their religion, and we know where we've heard that before.