Why to Christians seem to think that their God ( not Jesus ) is different than the Judaic or Islamic God?

The teachings, commandments, and descriptions of God in the Bible are very different from those of the quran. Not only that, but Jesus said to a group of Jews who claimed to worship God (e.g. "the God of Abraham"), "You have never heard his voice nor seen his form, nor does his word dwell in you, for you do not believe the one he sent."