The first Federal provision for public education in the US dates to 1785, when section 16 of each township was reserved for public school maintenance. So 'government schools', as you put it, predate even our constitution.
So I would say that defending public schools isn't secularist or evolutionist, it's conservative. And people who want to abolish such a basic and traditional part of American society are radicals.
Next thing you know those atheistic pinkos will be supporting government run fire departments and a standing army.