Kids in the public school and private are already taught by openly gay people and atheists and non-Christians.
The only way to avoid this is to teach them yourself. But they eventually have to enter the real world with people other than duplicates of themselves.
And by that time, they are more grounded in their faith.
I homeschool through 8th grade and send the kids to the public school for 9th grade. My kids have been well taught before that regarding their faith and how to think with a Christian worldview and they have done quite well.