[Because his father was a broken man, made so by magic - and he was raised his whole life to believe it was evil, and then lost both his parents to it and then had a war against a sister with magic who hated everything he was and stood for and he was prejudiced? Not that he's about to say all of that to you.]
Perhaps you would be better served asking others from Camelot. Undoubtedly they'd give a better explanation than I could.