Nobody ever claimed that the introduction was "the true word of God." That's the part that was changed. Somehow you just don't seem to be grasping that.
I understand that completely. What you seem to be glossing over (or not appreciating) is that the statement in question in the preface was
based on something. Now, unless I've missed something important, it's a reasonable conclusion that the statement that Israelites are the "principal ancestors of the American Indians" was based on a plain reading of the text of the Book of Mormon. If not, what
was it based on? And why would Mormon Church leaders allow something like that in, if it had no basis in scripture?
There was little reason not to. Most Christians 200 years ago believed the earth was created in six 24-hours days. When scientific findings indicated that it took much longer than that, many Christians accepted that, and began to understand that the scriptural account of the creation was probably never intended to be interpreted literally.
Right, which is similar to what I described with the Bible and the characteristics of the earth.
But that brings up a larger issue. Suddenly the "true word of god" isn't so plain and true after all, is it? Apparently for centuries, leaders and believers can all agree on one fact that stems from a direct reading of scripture, but have all that turned on its head via a finding of science. That begs the question: What was wrong with the leaders before? Did they not know how to read their own scriptures? They were completely oblivious to the now-fact that the scriptures in question actually meant something totally different?
If so, what does that say about the "true word of god"? Apparently this god isn't very good about conveying his true message. One also has to wonder: What's next? Just looking at Mormonism, for much of its history, "celestial marriage" was seen as fundamental tenet and extremely important to the faith (even to the point where it was practiced and advocated strongly by its founders). But when it's politically expedient, suddenly that changes (and to the exact opposite, where it's now forbidden).
To be fair, this is hardly unique to Mormonism. All religions change over time, and as we discussed, that by itself is no big deal. But when one claims from the beginning to be the "true word of god", but then starts changing things based on political convenience, social trends, or whatever, that kinda calls the whole "true word of god" thing into question.
It looks more like "We just made all this up and we can change any of it as we please".
When the book was first published, little was known about trans-continental migrations from to the American continent. As we came to understand the various ways the Americas came to be populated, the introduction to the Book of Mormon was revised accordingly. Nothing within the text of the book was changed because the book never made a statement one way or the other.
So what the heck were the people who wrote the original introduction going by? They just made stuff up? And no one from the Mormon congregation called them on it?