You don't believe terrorists are already here?
Yes, but this thread isn't about the IRS.
Just for the sake of argument, I'll accept that you may be as inane as that question suggests.
1) The islamotrash are here.
2) A portion of their support network is here as well.
They are allowed to remain here, and move about freely, because their presence provides an excuse (there's that word again) for those who seek to restrict the rights and freedoms of all Americans.
Ideological profiling, internment and deportation would eliminate the need for restrictions on society as a whole.
The islamotrash, as a group, are simply low level operatives who don't even realize how or why they're being used.