Signature phrase of Marshfield candidate upsets Imam Talal EidMARSHFIELD - The slogan appears right below Steve Barber’s name every time he posts a message on the popular Marshfield Forum online discussion board: ‘‘Killem All Let Allah Sort Em Out.’’ Where other forum users punctuate their messages with quotations or song lyrics, Barber uses a contemporary riff on ‘‘Kill ’Em All, Let God Sort ’Em Out,’’ a war cry coined by U.S. special operations forces during the Vietnam War. ‘‘I figure we’re fighting Muslims. ‘Allah’ works,’’ Barber said. Barber, 49, is a retired Army staff sergeant who, for the third time,...