The Book of Mormon 16/18
Another thing that causes me to doubt the Book of Mormon is a translation of an ancient American document is that it quotes or alludes to parts of the Bible that were written after Lehi left the land of Jerusalem and went to America. There are far too many of them to list, so I'll only list a few. If you're fairly familiar with the Bible, I recommend reading the BOM, and you'll see what I'm talking about.
2 Nephi 6:5-8:25 (and other places, e.g. Mosiah 14:1ff) quote from Second Isaiah (i.e. Isaiah 40-55), saying, "And there are many things which have been spoken by Isaiah which may be likened unto you, because ye are of the house of Israel. And now, these are the words..." In all fairness, there's dispute about when Second Isaiah was written. The more conservative scholars will say it was written before the exile by Isaiah himself, but most people think it was written during the exile by somebody other than the Isaiah of First Isaiah (i.e. Isaiah 1-39). I'm not sure myself, but I lean toward the majority.
2 Nephi 2:5 says, "And by the law no flesh is justified," which is just what Paul said in Romans 3:20.
Alma 5:38-39 says, "Behold, I say unto you, that the good shepherd doth call you; yea, and in his own name he doth call you, which is the name of Christ; and if ye will not hearken unto the voice of the good shepherd, to the name by which ye are called, behold, ye are not the sheep of the good shepherd. And now if ye are not the sheep of the good shepherd, of what fold are ye? Behold, I say unto you, that the devil is your shepherd, and ye are of his fold." This passage is a clear allusion to the parable of the good shepherd in John 10.
Alma 5:52 says, "And again I say unto you, the Spirit saith: Behold, the ax is laid at the root of the tree; therefore every tree that bringeth not forth good fruit shall be hewn down and cast into the fire, yea, a fire which cannot be consumed, even an unquenchable fire." John the Baptist said the same sort of thing in Luke 3:9.
Alma 19:10 says, "And Ammon said unto her: Blessed art thou because of thy exceeding faith; I say unto thee, woman, there has not been such great faith among all the people of the Nephites." That's an allusion to Luke 7:9 where Jesus says, "I say to you, not even in Israel have I found such great faith."
Alma 26:12 says, "Yea, I know that I am nothing; as to my strength I am weak; therefore I will not boast of myself, but I will boast of my God, for in his strength I can do all things; yea, behold, many mighty miracles we have wrought in this land, for which we will praise his name forever." Alma is alluding to Philippians 4:13 which says, "I can do all things through him who strengthens me," and 2 Corinthians 10:17 which says, "But he who boasts, let him boast in the Lord" and 2 Corinthians 12:5-10 where Paul talks about the thorn in his flesh.
Alma 38:13 says, "Do not pray as the Zoramites do, for ye have seen that they pray to be heard of men, and to be praised for their wisdom." In Matthew 6:5, Jesus said, "And when you pray, you are not to be as the hypocrites; for they love to stand and pray in the synagogues and on the street corners, in order to be seen by men. Truly I say to you, they have their reward in full."
Mormon 9:27 says to "work out your own salvation with fear and trembling before him," which is just what Paul said in Philippians 2:12.
In Ether 8:10ff there a story that closely parallels the story in Mark 6 about the beheading of John the Baptist.
Ether 12:6 says, "faith is things which are hoped for and not seen," which comes from Hebrews 11:1, and the rest of Ether 12 parallels the discourse on faith in Hebrews 11.
Moroni 7:45 says, "And charity suffereth long, and is kind, and envieth not, and is not puffed up, seeketh not her own, is not easily provoked, thinketh no evil, and rejoiceth not in iniquity but rejoiceth in the truth, beareth all things, believeth all things, hopeth all things, endureth all things." That comes from 1 Corinthians 13:4-7, which says in the KJV, "Charity suffereth long, and is kind; charity envieth not; charity vaunteth not itself, is not puffed up, Doth not behave itself unseemly, seeketh not her own, is not easily provoked, thinketh no evil; Rejoiceth not in iniquity, but rejoiceth in the truth; Beareth all things, believeth all things, hopeth all things, endureth all things."
Moroni 10:8-17 comes from 1 Corinthians 12:4-11. It says, "And there are different ways that these gifts are administered; but it is the same God who worketh all in all; and they are given by the manifestations of the Spirit of God unto men, to profit them. For behold, to one is given by the Spirit of God, that he may teach the word of wisdom; And to another, that he may teach the word of knowledge by the same spirit...And again, to another, the interpretation of languages and of diverse kinds of tongues. And all these gifts come by the Spirit of Christ; and they come unto every man severally, according as he will."
Dagoods asked me a while back what criteria I would use to determine whether there was a dependence between sources. I didn't have a clear set of criteria, but one criteria I said I think establishes a literary dependence is the use of exact wording. But these parallels in the BOM are enough to convince me that there was a literary dependence. The BOM obviously borrows from the New Testament which, if the story is true, the authors of the BOM could not have possibly been familiar with. That leads me to believe the BOM is not a translation of an ancient document, but was a document written by somebody who was familiar with the New Testament--somebody like Joseph Smith and his friends.