They're all from the same source and they're really the same religion. It's just that each of the messengers have come with a different name. They don't have a Bible. They have the teachings of this person, Baha'u'llah, who was their prophet from the 19th century. They also read from the Bible, the Torah and all of these kinds of things.
Most people find it really interesting, though.
It started in 1863. We believe in progressive revelation, which is all of the prophets came and brought teachings for their religion. As time went by, the people needed something new. She said that at 15 you get a choice. It's your responsibility to say whether or not you believe or to go investigate something else.