"It is the ideology, not just the terrorism, which is the problem. For example, a man is a threat when he believes Sharia should govern Canada, Jews are the descendants of apes and pigs, women are inferior beings, gays should be stoned to death and that the West is intentionally keeping Islam down. Regardless of his views on violence, which could easily change at any minute."
Not that I agree with any of that stuff, but it seems to me that you have a right to think those things in a free society. The threat is when you are motivated to strap a bomb to yourself.
Up to a point. In the U.S., the Constitution is the Law of the Land. This is not debatable and not up for vote.
I suppose you could introduce Constitutional amendments that would nullify portions of the Constitution and add amendments that are taken from Shari'a law. But getting amendments through is a laborious process and success is never guaranteed.
Now if you propose to replace the Constitution by force and overthrow the government of the U.S. by violence, that is treason, a hanging offence.
So if the Muslims in the U.S. think they can make Shari'a law the Law of the Land, they have a whole lot of procreating to do.