Two things are at play here -
Hamas/Palis are automatically supported by the left because they are the “underdog”, no matter how evil they are - they are the weaker minority in this conflict, so the left supports them.
Hamas/Palis are automatically supported by the left because they seek to kill Jews, God’s people.
And leftist American Jews must be afflicted with Orwell's "doublethink" from 1984.