It would take too much common sense (something liberals lack) to believe the hostile words of an enemy like Iran when they say they want to kill you. It is so much more soothing to believe that you have elected a savior who is looking out for your best interests than to believe you voted for a Manchurian Candidate who wants to fuel the fire against you.
(But to believe what Iranian leaders say, repeatedly, would be Islamophobic. Or something. — DM)