The Islamic terrorists have openly stated their intention to infiltrate their members, in with refugees.
Each one of those intends to do what the San Benardino wife did, which was to kill 14 innocent Americans, or more.
So let us consider the odds. On one hand, we refuse entry to any of them, so nobody gets through, or we subject ourselves to a number of dead Americans, to give us the warm fuzzies and feel-goods.
Muslims will lie, to further islam. They call it "Taqiyya," and it is part of their religion.
I experienced Islamic deception first hand, during the embassy hostage taking event in Iran in the 1970s, and will never forget.
I would not risk a single American life, on the chance of making no mistakes with screening/vetting refugees. I simply do not trust them.
We should provide funds and resources for safe places, near their home countries. But no muslim admittance to the US, period. Christians and Jews, fine.
Events spanning the late 70s to now, have only reinforced my concerns about islam. I have had professional dealings with Christians and Jews from Egypt, Syria, Jordan, Iran. When they know you well enough to "let their hair down" they will influence you along the lines I speak of.