That's how he was raised!
Rev Jeremiah Wright later taught that hate for 20 years while Obamah sat in the first-row pew.
Not just Rev. Wright but all the people around him, as he was growing up, both in Indonesia and the U.S.
By the time he was a teenager, the left had stopped supporting Israel and switched to the PLO etc.
As an aside, the left orginally supported Israel, Stalin
recognized the state of Israel about the same time the U.S. did. He saw Israel as counter weight to the conservative Arab states. Also, many Jews from Eastern Europe were socialists.