He isn't very powerful or 2. He isn't willing to tell us the true story. If God is willing but unable, He is impotent and thus not God. If God is unable and unwilling, He is evil and impotent Only if God is willing and able to convey to humanity a true, historical account, is God a supreme, loving, being. The historicity of the resurrection is critical to Christianity and if God shows himself to be faithless in other areas, why should I believe this story.
Historical veracity is important to the claim of divine inspiration.
There is a certain level of problematical events I am willing to accept, but my limit is not very high. If I beleive that the historical inaccuracy of the Bible was as bad as the book of Mormon, I would not be a Christian. It leads one to being able to believe contradictory things. Science can be believed and religious things can be believed even if they absolutely contradict each other. If all I have to do is merely believe, then there is no limit to what I am allowed to believe.