Why can’t agnostics who have a genuine Christian hope be admitted into the church? The baptismal requirements do not say one must believe in the Book of Mormon. Why is hope not enough?
Your question doesn’t make a whole lot of sense. An agnostic is someone who doesn’t think there is enough information to determine if there is a God. He takes a skeptical approach to questions. Someone with genuine Christian hope is one who has faith in Christ, who believes and hopes in the atonement and resurrection. Thus the person you are describing seems to be a paradox. Perhaps you meant something else?
Having faith in Christ is a requirement for baptism. An agnostic who gains faith in Christ is no longer an agnostic. Some other requirements for baptism are the willingness to repent, obey the commandments, and join with the Church.
Someone who does not believe in the Book of Mormon would presumably also not believe in Joseph Smith as a prophet, modern revelation, and pretty much the Church itself. Those ideas, those doctrines, are pretty foundational and fundamental to the Church of Jesus Christ of Latter-day Saints. A person can’t really be said to be willing to join with the Church if he rejects the foundations upon which the LDS religion is based.