What constitutes extreme vetting? How do we weed out extremists?

What about our homegrown extremists from other religions? Do we expel them from our country? Would we expel a domestic terrorist like McVeigh? Islam is not the only religion that is a harbinger of extremism. 

This nationalist idea of protecting the homeland from the miniscule percentage of extremists within a religion is prejudice hiding behind the promise of being safe in our own country. They are two separate issues.

If we are forced to sacrifice our ideals are we really living in freedom? Are we espousing the American way?