The Book of Abraham isn't one of the ones that was much of a factor in my choice to leave, but the bit I've learned of it was one of the many nails in the coffin. When reading the essay on the church's website, I was flabbergasted at things they said, over and over, and many are worth noting.
Here's some quick background first (although you should just read the essay). The early Mormons purchased four mummies and some papyri from a travelling entrepreneur in Kirtland, and Joseph Smith declared the papyri to be the Book of Abraham, which he then began to translate. The Rosetta Stone had not yet been found, so Egyptian was as yet unreadable. Joseph Smith's translation process included writing out many of the hieroglyphs with their "meanings" next to them, which still exists. When the early Mormons left Nauvoo, the artifacts didn't travel with them, and eventually a portion of them were destroyed in the Great Chicago Fire, but the surviving pieces were later discovered at another museum and repossessed by the church.
Even before the fragments were rediscovered and reclaimed, Egyptologists had been asserting that Joseph Smith's explanations for the facsimiles were wrong. When the fragments were examined by Egyptologists, who by that time could translate ancient Egyptian, they were found to be merely ancient funerary texts commonly buried with mummies, and were dated sometime between 300 B.C. and 100 A.D; long after Abraham's time.
By His Own Hand...
The article asserts many hypotheses for the discrepancies between what is on the fragments of papyrus versus what Joseph Smith "translated" into the Book of Abraham. Most of these hypotheses are shut down by one statement in the introduction to the Book of Abraham.
"...written by [Abraham's] own hand, upon papyrus."
It is clear that Joseph Smith really did assert that the papyrus contained the actual Book of Abraham and that he was literally translating them, and wasn't just a catalyst for revelation. In the History of the Church vol. 2 pg 236, it says,
In light of these two statements, these assertions from the essay seem quite weak:
" I commenced the translation of some of the characters or hieroglyphics, and much to our joy found that one of the rolls contained the writings of Abraham, another the writings of Joseph of Egypt, etc.,—a more full account of which will appear in its place, as I proceed to examine or unfold them. Truly we can say, the Lord is beginning to reveal the abundance of peace and truth." (emphasis mine)
"...the fragments do not have to be as old as Abraham for the book of Abraham and its illustrations to be authentic."
"...the physical artifacts provided an occasion for meditation, reflection, and revelation. They catalyzed a process whereby God gave to Joseph Smith a revelation about the life of Abraham, even if that revelation did not directly correlate to the characters on the papyri."
Denial of Biblical Teachings and Legendary Embellishment
The essay asserts that,
"The book of Abraham’s status as scripture ultimately rests on faith in the saving truths found within the book itself as witnessed by the Holy Ghost."Yet the Book of Abraham contradicts the Bible in a few ways. I was utterly floored when reading the essay when blatantly affirmed the denial of creation ex nihilo, which is made clear in the opening chapter of the Bible. The existence of preexisting matter would mean that God is not alone eternal and affirms the teachings of the church that there are generations of gods who have each formed their own "worlds," even though another of their essays denies that exact teaching.
There was a point that matter, time, and space did not exist. The Bible says so, and science and logic support this. To deny such a thing is a glaring error.
To make it worse, some of the "support" for the Book of Abraham given in the essay is from legendary embellishments on the stories of Abraham that date well over a thousand years after Abraham was in Egypt. We see in the legends that cropped up about Jesus a couple hundred years after his death that legendary, late stories are unreliable, yet this is exactly what the LDS church is using to support this book of "scripture."
And again, the Bible is denied when the Book of Abraham teaches about "Abraham’s being 62 years old when he left Haran, not 75 as the biblical account states."
Denial of both biblical truth and about scientific reality is a red flag if I ever saw one.
It's False, But You Should Believe It's True
That is exactly how the conclusion reads. After admitting the reality of the papyri being simply an Egyptian funerary text (and then downplaying that reality repeatedly), the essay concludes by essentially saying that the truth contained in the book--the Bible-contradicting, reality-contradicting "truths"--are the only way to tell if it's truly a book of scripture, and that that truth can't be found in history or scholarship.
I would bet that if it had been historically verifiable, they would be trumpeting the support for its truth.
Some of the best support for the Bible includes its historicity and it's manuscript evidence.The Book of Abraham is nothing like that, and even has reasons to disbelieve it's historicity and authenticity.
And yet we're supposed to believe it's true.