A lot of ink getting spilled yet no one seems to be able to tell us what "extreme vetting" is compared to "ordinary vetting".

Just what does "any cause for concern means rejection" mean, exactly? What is considered a "cause for concern"? Asking people if they intend to blow people up and they say yes?

Experience has shown that the danger lies in young people who feel "alienated" from society because it is not Muslim and does not follow shariah law. 

We have two options - change our society so it follows shariah law, or  refrain from accepting as immigrants people who believe our society should be run by shariah law, and teach their children that.