He wobbles on the political tightrope with his prior support for Hamas & Hezbollah and perceived greater sympathy for Palestinians which won't win him many friends in Jewish quarters - overall I agree he's not a racist per se but he'd better try to simply condemn needless waste of lives on both sides, but difficult for him as he's developed over a long time his anti-establishment / protest attitudes and style over any finesse in his leadership skills.The bloke plainly is neither a racist or anti semitic in its accepted meaning.
https://en.wikipedia.org/wiki/Political_positions_of_Jeremy_Corbyn#Hamas_and_Hezbollah