There are some great articles on this topic so I will not "reinvent the wheel", in terms of the documentation on this. The bottom line is that documentation CLEARLY shows this book was an invention of Joseph Smith, and did not come from God and is not as ancient as it is said to be.
For those unfamiliar with this subject, the Book of Abraham is a part of the official scripture in the Mormon "Pearl of Great Price" and was supposedly written by the Biblical Abraham, which, if true, would make this the very oldest Biblical text in existence!
Where did the papyrus come from that Joseph Smith supposedly translated into the Book of Abraham? Anthony Sebolo got the papyrus from near the city of Thebes in Egypt in the year 1831. Sebolo died in 1832, but willed the mummies and papyrus he had to his nephew, Michael Chandler, who eventually brought them to the United States and displayed them on a tour of the country. The Prophet Joseph Smith bought four of the mummies from Michael Chandler for $2400. With the mummies were found several papyri, some of which Smith indicated contained the writings of both Abraham and Joseph, who was sold into Egypt. It was from among these records that the Book of Abraham was translated.
While Egyptian hieroglyphics had not been deciphered in Smith's day, they have been since then. The papyri were lost soon afterwards and thought to have been destroyed in a fire in Chicago in 1871. There was, therefore, no way to validate Joseph's translation.
In 1966 some fragments of the papyri were rediscovered in one of the vault rooms of the New York’s metropolitan Museum of Art. The Deseret News of Salt Lake City on Nov. 27, 1967 acknowledged the rediscovery of the papyri, stating: "Included in the papyri is a manuscript identified as the original document from which Joseph Smith had copied the drawing which he called 'Facsimile No 1' and published with the Book of Abraham."
Subsequent "reading" of the hieroglyphics by Mormon and non-mormon scholars showed NO correlation between the papyri fragments and the Book of Abraham. It was a common funerary text that often was prepared to be buried with people by the Egyptians, and the drawings were of Egyptian gods in part. Later the church suggested that the rediscovered papyri were NOT the ones used for the Book of Abraham translation. But this appears to be just a way out of the dilemma. On the back of the papyri were "drawings of a temple and maps of the Kirtland, Ohio area". Before they were deciphered the church owned them as the correct ones.
A statement by Dr. Hugh Nibley, who was at the time a top authority in the LDS Church on the Egyptian language, warned: "The papyri scripts given to the church do not prove the Book of Abraham is true... LDS scholars are caught flat footed by this discovery." (Dec. 1, 1967, The Daily Universe - a BYU publication)
FACSIMILES: CARM.org (search there under Book of Abraham) shows them. Several sites have them.
In addition to these rediscovered papyri, the church has long had a collection called the Egyptian Alphabet and Grammar, which meant that the church had both the papyrus from which Smith translated, and also the original handwritten manuscripts which show the characters Smith used to make different portions of the Book of Abraham. One amazing pattern is seen: Smith would take from the papyri a single, simple figure and then translate it into MANY many words. For example, Book of Abraham 1:13-14 was translated from a single symbol not much more complex than a backwards capital letter E....and yet there are 76 words in it including some complex names of people and places! The problem with this pattern is that Smith said it was "translated from the papyrus" by him... not by direct (expansive) revelation. More on this is at Utah Lighthouse Ministry's website.
What do the papyri really say? They speak of Osiris Hor (Egyptian gods), a book of breathings, and how it is wrapped around the dead person who will breath like the souls of the gods for ever and ever. This general interpretation was given by several Egyptologists.
Many who have learned this information have left the LDS church. If THIS "translation" is bogus, what can we conclude regarding the "translation" of the Book of Mormon? For more on this topic, click here: Origins