A Columbia student and Israeli soldier tried to reason with the hundreds of anti-Israel protesters that rallied at the Morningside campus Wednesday. Guy Sela, 29, told The Post that he attempted to describe how he witnessed first-hand the horrors Hamas unleashed on his people and own family — but was only admonished as a “murderer.” “Never in my life I’ve seen something so inhuman as raping a young woman and decapitating her. And I’ve seen it firsthand,” Guy Sela, 29, told The Post as the group screamed behind him. “I’ve seen the babies that are lying there on the floor....