Think of it like a movie. The Torah is the first one, and the New Testament is the sequel. Then the Qu'ran comes out and it retcons like the last one never happened. There's still Jesus, but he's not the main character anymore, and the Messiah hasn't shown up yet.
Jews like the first movie, but ignore the sequels, Christians think you need to watch the first two, but the third movie doesn't count, Muslims think the third one was the best, and Mormons liked the second one so much that they started writing fanfiction that doesn't fit with ANY oi the series canon.
