Some of the people I mentioned absolutely reject scientific concepts in the schools. They tell their children to do the work but they see it as a necessary evil. I think they see themselves as the "faithful children of God suffering in this savage land". When I've made the mistake of engaging such people in conversation on the subject, they humor me as if I was mentally ill. Sometimes they pity my ignorance and try to show me the path to salvation.
I think the majority of American Christians are as you described; the watered down version. They're not so rapped up in it that they dismiss common sense and science, they are not really noteworthy. The extreme Christians are the real freak show. My father was born in Poland before WWII, raised VERY strict Roman Catholic and only got a third grade education. I give him a pass for his ignorance. I'd like to think that if he had been better educated he would have been able to separate scientific reality from religious traditional teachings. Christians born in this country in modern times who ARE exposed to science through the public school system have no excuses, they CHOOSE ignorance.
Let me be clear, both my wife and I have rejected superstition in favor of reason. We are raising our children to be rational, thinking, reasonable people. This does not sit well with our families.
I think you're asking these questions for the sake of your children's education. I think that if you talk to your children you can make them understand that science is reality and religion is kind of a balm for the spirit. The very young won't understand this; kids are pretty literal. Be careful. If they think you've lied to them it could damage your relationship with them for life. One way or the other the realization that what they've been taught is wrong will be painful for them, more so if they believe their parents were complicit in the deception.
I'll tell you how it was for me. I was raised as a Roman Catholic. I went to a Catholic school up to eighth grade, then a public high school. Somewhere along the line I realized that there was a conflict between what I was being taught in science class and what the Church was teaching me. I decided at quite a young age that science was right, but it took a few years of investigating and asking questions to figure out why the Church (and my parents) were lying to me. I asked questions in school, at home, and even went to see a priest at his home. I was always put off with standard platitudes: "It's important to keep the faith, my son." "This is what we believe." "Pray to God and he will guide your thoughts." I was probably fifteen or sixteen when I finally cornered a priest into answering my questions. He saw that I wasn't satisfied and wanted real answers and I guess he figured I was old enough to understand. He told me that the Garden of Eden story (that was the specific subject) was allegorical and not to be taken as literal fact, but that the majority of people couldn't handle that. Priests of course are educated men and sophisticated in their beliefs, but the unwashed masses must be patronized. (My words, not his). I finished out my Confirmation only because my parents expected it, and then I stopped going to church. I've spent the intervening years purging myself of the Roman Catholic conditioning. I've studied and learned all I could on the subject of religion and how it influences our lives, and I strive to not let it. I have pity for those who are caught up in religion through no fault of their own and only contempt for those who choose it willingly.
I hope I answered your questions, sorry it's so long!