We homeschooled, but "threw our son into the pit of filth" (your words, not mine) when he was 15 (he dual enrolled in college, never went to high school.) Going to college and still living at home during your high school years is a great thing. They come home and discuss what has been taught, and you can have meaningful conversations how to discern a prof's agenda, a text's bias, etc.
Our son graduated college at 19, and is in grad school. His faith is strong, he has not been seduced to "the dark side," politically or spiritually.
"Bring up a child in the way he should go...and he will not depart from it." We've raised them to know the Truth, and the Truth sets them free. They can be exposed to "filth" and know it is "filth." You can't isolate them from the world forever.