One of my sons is home schooled and the vast majority of his classmates is a Christian of some bent or other.
We are Christians but we chose to home school him because he wasn't getting the one on one attention he needed.
My other two sons are honors students with GPA's of 3.83 and higher. My five year old is well on his way to being a super kindergardner.
As I have talked to many of these Christian parents they believe that the public schools foster too many of the worldly ways and vices; they believe that immersing their children in this environment will lead to things like cussing, teen pregnancy, abortion, illicit drug use and a general spoiling of their childs mind.
My two high school sons attend the public school where I live.
As a Christian man I don't believe in taking them out of the society nor am I particularly worried that they will become victims of drug use, sex, std's...and the plethora of other vices bred by the society at large.
My faith dictates that I raise them in faith believing God and that they will go on to change the world they live in as opposed to being changed by the world they live in.
So far so good. They see what other kids are into; they talk to us often about those things. Our communication is good.
The problem with taking your children completely out of the social order of society is that it makes them more susceptible to its temptations. I grew up with church kids who absolutely went crazy when they got their first taste of freedom. Sex, drugs...you name it they got into it.
A monitored exposure to these things, prayer and open communication is what you want. Not isolation. Besides Jesus was in the society not of the society.