Trump Calls for Complete Ban on Muslims Entering the United States

Recently, Presidential candidate Donald Trump said that he believes we should temporarily not allow any Muslims into the United States except those who are returning citizens (see links below).  He believes we are at war and that there is precedent for this type of measure. 

Does anyone have any thoughts about this?  Do you think Trump is being too extreme?  Do you think such a measure is justifiable?

LINK 1

LINK 2

Source: Orthodox Messianic Judaism (http://goo.gl/tTgTQM)