Last time I spoke to Mormon missionaries I asked them about plagiarism on the BOM.
The gospels of Matthew, Mark and Luke all contain a record of the Sermon on the Mount. They offer three similar but quite different accounts. One writer includes parts that the others leave out and so on. Actually I think they are contradictory but that's another thread.
Mormons believe that after his resurection Jeus went to America and delivered a similar sermon. The sermon delivered to the people in America is delivered in a different language from the Aramaic Jesus spoke in Palestine and which was written down in Greek. Now when the gospels are translated out of greek into 17th century english (KJ version) we find three quite different accounts. When we read the parallel account in the BOM we find it is identical word for word to Matthew's version as found in the KJ.
So here is what you have to believe to accept the book of mormon as genuine..
That Jesus went to America and despite the people having different circumstances from the Jews of Palestine he delivered exactly the same sermon - he didn't change a single word, not one!
Despite his speaking in a different language and his words being recorded in another language when the golden plates are traslated from this ancient language into 19th century english lo and behold it comes out identical to the 17th century English traslation of Matthews account of Jesus' sermon given in Palestine.
But the smoking gun of plagerism is still to come. You know when the teacher was trying to work out who copied homework from who? The real evidence is when you are both stupid enough to make exactly the same mistakes. Well keep going to the lords prayer. In all old manuscripts it ends before the line in the King James version of Matthew about "for yours is the kingdom and the power and the glory for ever and ever amen" Clearly these lines were borrowed from Revelation sometime to make Jeus words into a piece of liturgy perhaps first in the margin of a manuscript and later it got included in the text. It does not appear in any manuscript before the middle ages. Well what do you know .... it's right there in the book of mormon version of the sermon.
Golden plates my arse!