Who is Mirza Husayn Ali from The Kingdom of the Cults and what is their importance?

Mirza Husayn Ali is the founder of the Bahai faith and called "Baha'u'llah." He claimed he played Christ to his predecessor, Mirza Ali Muhammad (known as "Bab"), who supposedly played the part of John the Baptist. Mirza Husayn Ali left behind 200 books and tablets for his followers.