Dangerous? Christian Reconstructionists advocate violence? Where in this dodgy article is it written that they train their homeschooled children to wear explosives into buses or fly planes into skyscrapers?
This is clearly a campaign of name-calling, and there is a lack of substantive argumentation on both sides. The source is a secular homeschooling support group, and there is nothing wrong with that (God bless 'em - tee hee), but the article and many of the comments are nothing but Christian baiting.
They haven't, yet
They are advocating converting this country to a Christian State and history demonstrates that that always ends up with the killing of dissenters and the end to freedom of thought and action.
Historically, Muslim States have been more tolerant of dissent than Christian ones. Currently Islam is in a Medieval period, and the Christian world is still more or less in a period of enlightenment, but that has changed before.