If you ask a Mormon if the Bible contains all the words Jesus or the apostles ever taught, then the short answer is “no.” Now, if you ask whether the Bible is complete, well, that’s a bit harder to answer because one would have to explain what they mean by such a question. How does one define “complete”? If by “complete” you mean perfect, then no, Mormons do not believe the Bible is perfect, assuming we have the same definition of “perfect”. If by complete you mean that it contains everything God ever said to man, then no, we do not think it is complete. If by complete you mean it contains everything of a spiritual nature ever written by a prophet or apostle, or every scripture that was ever written, then no, we do not believe it is complete. If by complete you mean it contains everything God wanted it to contain…well, maybe?
Mormons do not believe the Bible is perfect, in the sense that when you read any of the widely available version of our day, you are reading the words exactly as they were written down by the prophets and apostles themselves. We do not believe in the concept of inerrancy, that is, the idea that the Bible of our day is exactly what was written down by the prophets and apostles. We believe the Bible came to us through the hands of many men over many centuries. It was translated from various languages into other languages, and then into others. These translations were made by men, using their education and knowledge as best they could. Most of these men were probably well-meaning and honest. Some were undoubtedly corrupt and removed passages of scripture and changed others so that the true meaning was lost. In other words, we believe the Bible to be the word of God, as far as it was translated correctly.
It is quite obvious from the Bible itself that it does not contain everything God ever said to man, nor everything he said to the prophets and apostles, nor everything Jesus said, etc. Here are a few examples:
Mark 6:34 – “And Jesus, when he came out, saw much people, and was moved with compassion toward them, because they were as sheep not having a shepherd: and he began to teach them many things.” Jesus taught “them many things.” What did he teach them? We don’t know. It’s not written anywhere in the Bible.
There are other examples as well, but this enough to show that there are things that you would expect to have in the Bible that clearly are not.
Now, for that last question–does the Bible contain what God wanted it to? I don’t know. Clearly it contains enough to get the job done that it was designed to do. But what exactly was it designed to do? Was it designed to contain everything God ever said to man? Evidently not. Was it designed to exist by itself, forever, and never be joined by the other scriptures we know are missing? What about scriptures that are missing, but which are not referenced in the Bible itself? Yeah, you know where I’m going with that, so we’ll just leave things there.