The god of the Old Testament, the god of the Jews, is a jealous god. He doesn't care about justice or mercy, he just wants you to fall down on your knees and worship him, and offer sacrifices of blood to him and not to any other gods. He wants all your worship. That's the only "monotheism" in the Old Testament -- "Worship me and nobody else, or I will punish you." Which is why the Gnostics rejected this god, because he isn't the Highest. He's just some trumped up mountain deity with pretensions.