Mormonism is a cult and nothing more, I'd advise your sister to stay clear of it and embrace the true Christian Faith. Keating writes an exceelent
expose on Mormonism:
"Ask the Mormons to produce any historical proof to support their claim that in the early centuries the Church was Mormon. They can’t do it because
there is no such evidence.
The Book of Mormon itself suffers the same fate when it comes to its own historical support. In a word, it hasn’t got any.
The Book of Mormon describes a vast pre-Columbian culture that supposedly existed for centuries in North and South America. It goes into amazingly
specific detail describing the civilizations erected by the "Nephites" and "Lamanites," who were Jews that fled Palestine in three installments,
built massive cities in the New World, farmed the land, produced works of art, and fought large-scale wars which culminated in the utter destruction
of the Nephites in A.D. 421. The Latter-Day Saints revere the Book of Mormon as the divinely-inspired record of those people and of Christ’s
appearance to them shortly after his crucifixion in Jerusalem.
The awkward part for the Mormon church is the total lack of historical and archaeological evidence to support the Book of Mormon. For example, after
the cataclysmic last battle fought between the Nephites and Lamanites, there was no one left to clean up the mess. Hundreds of thousands of men and
beasts allegedly perished in that battle, and the ground was strewn with weapons and armor.
Keep in mind that A.D. 421 is just yesterday in archaeological terms. It should be easy to locate and retrieve copious evidence of such a battle, and
there hasn’t been enough time for the weapons and armor to turn to dust. The Bible tells of similar battles that have been documented by archaeology,
battles which took place long before A.D. 421.
The embarrassing truth—embarrassing for Mormons, that is—is that no scientist, Mormon or otherwise, has been able to find anything to substantiate
that such a great battle took place.
"Lifting" from the King James Bible
There are other problems with the Book of Mormon. For example, critics of Mormonism have shown convincing proof that the Book of Mormon is a synthesis
of earlier works (written by other men), of the vivid imaginings of Joseph Smith, and of simple plagiarisms of the King James Bible.
The only Bible that Joseph Smith relied on was the King James Version. This translation was based on a good but imperfect set of Greek and Hebrew
manuscripts of the Bible.
Scholars now know the Textus Receptus contains errors, which means the King James Version contains errors. The problem for Mormons is that these exact
same errors show up in the Book of Mormon.
It seems reasonable to assume that since Smith was a prophet of God and was translating the Book of Mormon under divine inspiration, he would have
known about the errors found in the King James Version and would have corrected them for when passages from the King James Version appeared in the
Book of Mormon. But the errors went in.
The "Fullness" of the Gospel?
According to a standard Mormon theological work, Doctrines of Salvation, one finds this definition: "By fullness of the gospel is meant all the
ordinances and principles that pertain to the exaltation of the celestial kingdom" (vol. 1, p. 160). That’s an official Mormon statement on the
subject. But there’s a problem.
If the Book of Mormon contains all the ordinances and principles that pertain to the gospel, why don’t Mormonism’s esoteric doctrines show up in it?
The doctrine that God is nothing more than an "exalted man with a body of flesh and bones" appears nowhere in the Book of Mormon. Nor does the
doctrine of Jesus Christ being the "spirit brother" of Lucifer. Nor do the doctrines that men can become gods and that God the Father has a god
above him, who has a god above him, ad infinitum.
The Book of Mormon is Anti-Mormon
These heterodox teachings, and many others like them, appear nowhere in the Book of Mormon. In fact, pivotal Mormon doctrines are flatly refuted by
the Book of Mormon.
For instance, the most pointed refutation of the Mormon doctrine that the Father, Son, and Holy Ghost are actually three separate gods is found in
Alma 11:28-31: "Now Zeezrom said: ‘Is there more than one God?’ and [Amulek] answered, ‘No.’ And Zeezrom said unto him again, ‘How knowest thou these
things?’ And he said: ‘An angel hath made them known unto me.’"
The Bottom Line
The Book of Mormon fails on three main counts. First, it utterly lacks historical or archaeological support, and there is an overwhelming body of
empirical evidence that refutes it. Second, the Book of Mormon contains none of the key Mormon doctrines. This is important to note because the
Latter-Day Saints make such a ballyhoo about it containing the "fullness of the everlasting gospel." (It would be more accurate to say it contains
almost none of their "everlasting gospel" at all.) Third, the Book of Mormon abounds in textual errors, factual errors, and outright plagiarisms
from other works.
If you’re asked by Mormon missionaries to point out examples of such errors, here are two you can use.
We read that Jesus "shall be born of Mary at Jerusalem, which is in the land of our forefathers" (Alma 7:10). But Jesus was born in Bethlehem, not
Jerusalem (Matt. 2:1).
If you mention this to a Mormon missionary, he might say Jerusalem and Bethlehem are only a few miles apart and that Alma could have been referring to
the general area around Jerusalem. But Bethany is even closer to Jerusalem than is Bethlehem, yet the Gospels make frequent reference to Bethany as a
Another problem: Scientists have demonstrated that honey bees were first brought to the New World by Spanish explorers in the fifteenth century, but
the Book of Mormon, in Ether 2:3, claims they were introduced around 2000 B.C.
The problem was that Joseph Smith wasn’t a naturalist; he didn’t know anything about bees and where and when they might be found. He saw bees in
America and threw them in the Book of Mormon as a little local color. He didn’t realize he’d get stung by them."
Here are a few links to have your sister look over:
Hope this helps.